The imam of the Mosque attended by Manchester Salman Abedi has revealed the suicide bomber looked at him 'with hate' when he gave a sermon criticising ISIS.

It comes as neighbours of the British-born Manchester United fan described his 'strange behaviour' in the weeks before he slaughtered 22 people.

The 22-year-old attacker, as an abrasive, tall, skinny young man who was often seen in traditional Islamic clothing according to neighbours, was heard 'chanting prayers loudly in the street' outside his home in the south of the city.

Abedi is the third of four children by Libyan refugees who came to the UK to escape the Gaddafi regime. They are believed to have lived in the Fallowfield area of south Manchester for at least ten years.

Last night, Abedi murdered and maimed concert goers as they left Manchester Arena after an Ariana Grande concert.

This is the moment anti-terror police swooped to arrest a man over last night's ISIS suicide bomb atrocity at Manchester Arena

Neighbours of British-born Manchester suicide bomber Salman Abedi have revealed his 'strange behaviour' in the weeks before he slaughtered 22 people

A forensic investigator emerged from the house carrying a booklet called 'Know Your Chemicals'

Mohammed Saeed, the imam of Didsbury Mosque and Islamic Centre (pictured), said Abedi had looked at him 'with hate' after he gave a sermon criticising ISIS

ISIS this morning claimed responsibility and threatened further attacks, saying 'one of the caliphate's soldiers placed bombs within a gathering of the Crusaders'.

Mohammed Saeed, the imam of Didsbury Mosque and Islamic Centre, said Abedi had looked at him 'with hate' after he gave a sermon criticising ISIS and Ansar al-Sharia in Libya in 2015.

He said the vast majority of people at the mosque were with him but a few signed a petition against him, reports the Guardian.

Mr Saeed said: 'Salman showed me a face of hate after that sermon. He was showing me hatred.'

Police were seen clutching a 'know your chemicals' manual as they carried out a raid at the property

He added that a friend was so worried for his safety that he got his adult children to sit beside Amedi in case he attacked the imam.

Police are trying to determine whether Abedi, a former Burnage Boys Academy pupil who appears to have been radicalised within the last couple of years, acted alone or was part of a wider terror cell.

Chemical experts were seen outside with specialist instruments amid fears that he could have obtained radioactive material.

It was also claimed that he had travelled by train from London to Manchester on Monday in advance of the attacks.

It raised suspicions that he may have met co-conspirators or been supplied with his explosive device by an as-yet-unidentified bombmaker.

There were unconfirmed reports that the whole family, apart from the two elder sons, recently returned to their native Libya.

It comes as dramatic pictures emerged showing anti-terror police swooping to arrest Abedi's 23-year-old broth Ismail in Manchester over last night's atrocity.

Abedi grew up in the Whalley Range area of the city, just yards from the school which hit the headlines in 2015 when twins and aspiring medical students, Zahra and Salma Halane, fled their homes and moved to Syria.

He was a business and management student at Salford University, enrolling in 2014. But, after attending lectures for two years he then stopped going.

Police are urgently trying to work out whether Salman Abedi, who killed 22 last night as thousands of young people were leaving an Ariana Grande concert, was acting alone or whether he was 'part of a network'

A father carries away his daughter away following the suspected terror attack at the Ariana Grande concert

He is registered as having lived with his mother Samia Tabbal, father Ramadan, a former airport security worker, and a brother, Ismail, who was born in Westminster in 1993.

Separate pictures show raids at what is believed to have been Abedi's home in Fallowfield, where a controlled explosion took place, and his brother Ismail's address, where a 23-year-old man was arrested.

One neighbour claimed they heard Abedi chanting Islamic prayers at the home just weeks before the concert hall atrocity.

This was the scene inside the Manchester Arena last night after the suspected terror attack at the teen concert

A major police operation is underway this morning to determine whether the suicide attacker who detonated a nail bomb at Manchester Arena last night was part of a terror cell

Forensic officers were seen emerging from the property carrying a police-issue booklet called 'Know Your Chemicals'.

Lina Ahmed, 21, told MailOnline: 'They are a Libyan family and they have been acting strangely.

'A couple of months ago he [Salman] was chanting the first kalma [Islamic prayer] really loudly in the street. He was chanting in Arabic.

'He was saying 'There is only one God and the prophet Mohammed is his messenger'.'

Abedi's former school friend Leon Hall told MailOnline he saw the killer last year and said he had grown a beard.

He also said the jihadist was a keen Manchester United fan.

Hall, 26, and Abedi lived close to each other in a row of run down terraced houses in the Moss Side area of Manchester.

They later ended up living next door to each other in a nearby street and went to the same school.

Hall said: 'I saw him last year and he had a beard thing going on. We didn't speak but just nodded to each other. I don't remember seeing him with beard before.'

Hall said they grew up playing together on the street around their home.

'He and I had a tussle many years ago when we were kids. It was over nothing, but he always had a bit of an attitude problem. I can't say I really liked the man.'

A large police presence, including armed officers, was seen outside an address about a mile from the scene of the arrest

Forensics wearing white suits were called to an address in Greater Manchester after a police operation

Aerial shots showed police descending on a house in Fallowfield, Manchester as part of the investigation into the bombing massacre last night

Hall, who was sat outside his home with his sister, said Abedi was a Muslim.

Other family members at the house, who asked not to be named, confirmed that Abedi was a Muslim.

Hall said:' I remember that he was a big Man Utd fan. I don't think he went to the games but would follow them.'

Abedi, who lived in a housing association owned home about two miles from the scene of Monday night's terror attack.

He later moved 400 yards away to another terraced home. The area is predominantly occupied by immigrants with many of the terraced homes housing newly arrived immigrants.

The current occupiers of the three-bedroom home where Abedi lived more than a decade ago said they had never met him or his family.

'They were already gone when we moved in,' said a woman clutching a small baby.

'We do not know them and have never spoken to them.'

Abedi is understood to have attended Claremont Primary School a short distance from his home.

Officers are combing CCTV to determine whether the attacker carried out a 'recce' of the arena before detonating a nail bomb as thousands were leaving the concert.

The suicide attacker is said to have been 'known' to the authorities and anti-terrorist officers are going through hundreds of hours of CCTV footage trying to 'pick him up' during his journey to the arena.

Officers also believe that he will have carried out a 'recce' to the giant venue in recent days and a separate team are studying footage going back into the past week.

Footage shows officers arresting a 23-year-old man outside a Morrisons supermarket in Chorlton-Cum-Hardy, south Manchester this morning

Police probing last night's terror attack said a 23-year-old man has been arrested outside a supermarket in south Manchester in connection with the arena massacre

Non-uniform anti-terror officers wearing masks to conceal their faces were seen emerging from a Black Mercedes before arresting a man outside a Morrison's in Chorlton

Forensic and bomb squad officers are studying the remains of the device recovered so far but initial indications are that the bombmaker had used a 'level of sophistication' suggesting he had received training and not made it from 'a terror recipe' on the Internet.

One security source told MailOnline: 'It is unlikely that if the device was sophisticated that the suicide bomber made it – experience shows that organisations are reluctant to 'waste' the expertise of a bombmaker in an attack, preferring to keep him or her for another attack.

ISIS WARNS OF MORE ATTACKS ISIS this morning claimed responsibility for the atrocity in a ranting statement that threatened further attacks on 'worshippers of the Cross. 'With Allah's grace and support, a soldier of the Khilafah managed to place explosive devices in the midst of the gatherings of the Crusaders in the British city of Manchester,' the statement said. It added that the massacre was 'revenge for Allah's religion… in response to their transgressions against the lands of the Muslims. 'The explosive devices were detonated in the shameless concert arena. 'What comes next will be more severe on the worshipers of the Cross and their allies.' Advertisement

'It is therefore highly likely that this terrorist is part of a cell or had a support network and they are the priority.

'Are there other devices, other terrorists out there and you can expect to see raids carried out in the next 48 hours linked to this.'

Detectives are also studying the bomber's links to Syria or other jihadi hotbeds amid intelligence that he may have travelled abroad to the region.

At least 16 convicted or dead jihadi terrorists are known to have come from a small area of Manchester and several surveillance operations on suspects from the region have been on-going.

Possible links to ISIS-inspired cells involved in the Belgium, Paris and Stockholm attacks are also being examined.

Less than 24 hours after the atrocity ISIS claimed responsibility for the murders.

The extremists were quick to call the killer one of their soldiers, as has become the trend in the wake of many recent attacks in Europe.

According to the SITE Intel Group, which monitors jihadist groups, the ISIS statement described the explosion as having taken place at a 'shameless concert arena'.

Casualties are stretchered out of the concert on Monday evening after a terror attack in the Ariana Grande concert

They appeared to wrongly state that a number of explosive devices had been detonated, when police have said the attacker was carrying one bomb.

Part of the investigation into what happened is probing whether the killer was acting alone or as part of a network. ISIS has previously encouraged lone wolf attacks against Westerners.

Monday night's carnage came as a result of a method described by some terror experts as more 'sophisticated' than other recent attacks in Europe.

The apparent suicide bombing tactic is markedly different from lone wolf Khalid Masood's car and knife rampage in Westminster earlier this year.

Theresa May this morning said that police believe they know the identity of the attacker.

Children were among the 22 people killed as the explosion tore through fans leaving the pop concert at about 10.30pm last night.

Some 119 people were also injured in the blast caused by an improvised explosive device carried by the attacker, who was also killed.

Experts say the bomber employed a 'sophisticated' method of attack using a a device packed with nuts and bolts, so-called 'dockyard confetti', to cause maximum damage.

Former police officer and counter-terrorism expert Chris Phillips described the latest attack to hit the UK as 'a step up'.

This distressing picture purportedly shows the inside of the arena after the suicide attack at the Ariana Grande concert - its veracity has been confirmed by the two witnesses

The identity of the attacker, who was also killed, is not yet known and the deadly blast is being treated as an act of terrorism

Eight-year-old Saffie Rose Roussos (left), from Preston, and 18-year-old Georgina Callander (right) have been named as victims. It is feared many children are among those killed, as well as parents who had accompanied their youngsters to the concert or were picking them up

He told BBC Radio 4's Today programme: 'I think the point is that this was obviously a planned attack and that will involve people looking at the venue and seeing how the venue operates.

'And also the fact that it sounds like this was a strapped on suicide belt and also from what we just heard, perhaps, with what we call dockyard confetti which is the little bits of nuts and bolts that are attached to the vest.

'And those unfortunately are there deliberately to kill people and that's the whole purpose of them. This does look like a step up and my worry, and I think the police's worry now, is that this person probably wasn't acting alone and there are other people that to be captured.'

Britain's terrorist threat level stands at 'severe,' the second-highest rung on a five-point scale, meaning an attack is highly likely. Counter-terrorism police have said they are making on average an arrest every day in connection with suspected terrorism.

For the second time in two months, police and security services are embarking on a major terror investigation.

A Twitter account - which was unverified - posted this four hours before the attack

Several ISIS-friendly accounts posted the hashtag #ManchesteArena and #ArianaGrande

None of the ISIS fan pages have claimed responsibility for last night's terror attack

The bomber is believed to have entered a foyer area of the venue through doors opened to allow young music fans to leave

As with the Westminster atrocity in March, in which five were killed, the most pressing question is whether the individual behind the Manchester blast was a so-called 'lone wolf' or part of a wider terror cell.

The working theory is that the perpetrator triggered the blast alone but the national police counter-terror network, assisted by MI5, are urgently piecing together his background to see whether he had any help in planning the outrage.

They will be looking to build a picture of the attacker's movements both in recent weeks and months as well as immediately before the strike.

Another priority will be to establish whether any further linked attacks or copycat incidents are planned.

It is likely that the bomber's communications will form a significant part of the inquiry, while investigators will also be checking if he was known to authorities in any way.

One area of focus will be examining the remnants of the device used in the attack as officers work to establish whether the perpetrator built it himself or had help.

As well as seeking to identify any potential accomplices in Britain, authorities will also be looking into the possibility of any link to international groups.

HOW BRITAIN HAS SUFFERED AT THE HANDS OF EXTREMISTS After Britain as struck by terror again, here are some of the terrible events suffered by the country at the hands of extremists in recent years: May 22, 2017: Twenty-two people - including children - are killed and around 59 injured during a terrorist bombing at a pop concert in Manchester. It is thought a lone suicide bomber detonated an improvised explosive device as crowds of music fans, many of them youngsters, left the Manchester Arena following a performance by US artist Ariana Grande. Concert-goers and witnesses have described the chaos after 'huge bomb-like bangs' went off in Manchester Arena following an Ariana Grande gig March 22, 2017: Five people are killed when an Islamist extremist launched a car and knife attack in central London. Khalid Masood drove a hired car over Westminster Bridge, near the Houses of Parliament, mounted the pavement and hit pedestrians before crashing into railings outside the Palace of Westminster. He stabbed Pc Keith Palmer, 48, to death and also killed US tourist Kurt Cochran, Romanian tourist Andreea Cristea, 31, plus Britons Aysha Frade, 44, and 75-year-old Leslie Rhodes. Masood was shot dead by police. June 16, 2016: Labour MP Jo Cox is murdered outside her constituency office in Batley, West Yorkshire. The mother-of-two, 41, was shot and stabbed multiple times by right-wing extremist Thomas Mair. He was later handed a whole-life prison sentence for her murder. Fusilier Lee Rigby was murdered by Islamic extremists Michael Adebolajo and Michael Adebowale December 5, 2015: A lone attacker attempts to behead a passenger during an ISIS-inspired rampage in the ticket hall of Leytonstone Underground station in east London. Somali-born Muhiddin Mire targeted strangers at random during the attack on December 5 2015 before slashing fellow passenger Lyle Zimmerman, 56, with a knife. The schizophrenic was sent to Broadmoor Hospital after being given a life sentence with a minimum term of eight years for attempted murder. May 22, 2013: Fusilier Lee Rigby is murdered by Islamic extremists Michael Adebolajo and Michael Adebowale. The 25-year-old serviceman was walking near his barracks in Woolwich, south-east London, when the pair rammed him with his car before attempting to hack off his head with knives. The killers were jailed for life at the Old Bailey in February 2014. June 30, 2007: Two men inspired by Islamist extremism ram a 4x4 laden with petrol and propane tanks into the main terminal of Glasgow Airport. One of the attackers died in the incident and five people were injured. July 7, 2005: Four suicide bombers kill 52 and injure hundreds of others in blasts on the London Underground network and a bus. Twenty-six died in the bombing at Russell Square on the Piccadilly line, six in the bombing at Edgware Road on the Circle line, seven in the bombing at Aldgate on the Circle line, and 13 in the bombing on a bus at Tavistock Square. Advertisement

In the first hours after an attack on this scale investigators will be sifting through a number of theories as they work to settle on the most likely lines of inquiry.

There was no immediate claim of responsibility. Supporters of the ISIS, which holds territory in Iraq's Mosul and around its de facto capital in the Syrian city of Raqqa, celebrated the blast online.

One wrote: 'May they taste what the weak people in Mosul and (Raqqa) experience from their being bombed and burned,' according to the U.S.-based SITE Intelligence Group.

Focus will now turn on why Manchester was selected as a target.

It comes two months after a 35-year-old man and a 32-year-old woman were arrested at an address in West Didsbury, Manchester on suspicion of preparation of terrorist acts.

The raids were linked to the Westminster attack that month in which Khalid Masood killed five and injured more than 50 by driving through crowds of tourists.

Earlier this year, Manchester-born jihadi Jamal Al-Harith was killed carrying out an ISIS suicide car bomb attack in Iraq.

Shortly after detonating the explosive-laden car near an army base, ISIS released a statement revealing al-Harith had been fighting for them under the name Abu Zakariya al-Britani.

Leaked ISIS documents later claimed he was recommended to the terror group by Raphael Hostey, a 24-year-old jihadi based in the northern city.

This graphic shows where the explosion took place, in the foyer area, leading towards Victoria railway station

Hostey is thought to have encouraged dozens of British Muslims to travel to Syria - including close friends Mohammad Azzam Javeed and Anil Khalil Raoufi - before being killed in a drone strike last May.

Last year, two British brothers from Manchester were killed fighting for ISIS in Syria.

Khalif Shariff, 21, and 18-year-old Abdulrahman are understood to have left their home in the city and travelled to the war-torn country in November 2014.

In 2015, Pakistani student Abid Naseer was convicted in a U.S. court of conspiring with al Qaeda to blow up the Arndale shopping centre in the centre of Manchester in April 2009.

In September, a Manchester florist was stunned after his image was used in an ISIS magazine.

Stephen Leyland, 64, was interviewed by counter-terrorism police after a photograph of him standing next to flowers was used in the Rumiyah publication.

The ranting 38-page magazine was one of many pieces of propaganda aimed at encouraging violence in the West.

It called for attacks on Britons and urged supporters of the terror group to take 'even the blood of a merry Crusader citizen selling flowers to passersby'.

Two months later, fanatics urged lone-wolf attackers to 'open the door to jihad' in a video showing how to make a bomb and decapitate people.

Greater Manchester Police chief constable Ian Hopkins revealed the suicide bomber 'was carrying an improvised explosive device'

Forensics have been called in to examine the scene as police attempt to identify the attacker

The instructional video, called 'Explanation of How to Slaughter Disbelievers', featured a balaclava-wearing terrorist in a kitchen explaining how to make bombs.

According to the terror monitoring group SITE, the bomb expert took viewers on a step-by-step guide on how to make deadly explosives.

Approximately 850 people from the UK have travelled to support or fight for jihadist organisations in Syria and Iraq, according to British authorities.

About half have since returned to the UK, with more than 100 people having been convicted for offences relating to the conflict.

Former global terrorism operations director at MI6, Richard Barrett, said, while the attack was more sophisticated than recent ones, it does not automatically mean the person responsible was trained abroad to carry out the massacre.

He told Today: 'I think people can build bombs, we have seen that in the past that it may be not that complicated to build a bomb which has an effect on the people immediately around you as this one certainly did.

'Yeah, sure that's a bit more sophisticated clearly than driving a car into people or stabbing them with a knife but I'm not sure that it requires somebody to go to Syria for example, to have training there to get that sort of expertise so I'm sure the police will be very interested indeed to look at whoever is responsible, what he has been doing over the last months.'

Witnesses reported hearing a 'huge bang' at the venue shortly after US singer Ariana Grande's gig finished

A child was spotted clutching a balloon while wrapped in a foil wrap following the terror attack at the Manchester Arena

Concert-goers helped injured people away from the gig last night. Witnesses describe the scene as 'like a warzone'

This photo shows the aftermath of the suicide bomb which ripped through the foyer of the venue killing parents and children

He said the security services face a 'real challenge' in monitoring potential threats and said investigations must involve 'engagement' with communities.

He said: 'I think in terms of additional security it's much more on that intelligence side, on engagement with the community, on trying to understand better why people do this sort of thing than it is on putting up more bollards or, as you say, moving the choke point of security just a bit further away.'

He described the attack, targeted at concert-goers including children, as 'very, very cynical'.

He added: 'That is why it is so important to understand, I think, whether this person was connected with other people, whether it was in some way directed by an organised group.

'What was the intention behind it, in the broader strategic sense?'

The Manchester attack was the deadliest in Britain since four suicide bombers killed 52 London commuters on three subway trains and a bus in July 2005.

Pop concerts and nightclubs have been a terrorism target before. Almost 90 people were killed by gunmen inspired by ISIS at the Bataclan concert hall in Paris during a performance by Eagles of Death Metal in November 2015.

In Turkey, 39 people died when a gunman attacked New Year's revelers at the Reina nightclub in Istanbul.

Manchester was hit by a huge Irish Republican Army bomb in 1996 that leveled a swath of the city center. More than 200 people were injured, though no one was killed.