Victims called on the government to 'take the gloves off' when dealing with terrorists and the internet companies that help them after a report found a series of failures ahead of last year's terror attacks.

Parliament's Intelligence and Security Committee said social media websites were being used as a 'safe haven' by extremists and called for an advertising boycott.

They also uncovered failings in how terrorists were handled by authorities, including how Manchester bomber Salman Abedi was allowed to visit an extremist in prison and travel back and forth to Libya before he killed 22 concert-goers.

Victims of the Manchester attack called for stronger action in the wake of the report.

Dan Hett, whose brother Martyn was killed in the attack, said: 'Of course we understand that mistakes will sometimes be made but the litany of mistakes in 2017 must urgently be learnt from.

'As survivors we echo the importance of social media companies playing a more active part in combating terror. We urge the government to take the gloves off in addressing their roles both as a safe haven and as a platform for spreading hate.'

Salman Abedi (left) went to see Abdalraouf Abdallah (right) who was jailed after trying to help other Manchester-based fanatics join extremists in Syria

Medics treat the injured after the suicide bombing at the Manchester Arena in May 2017

The report found:

Internet firms are failing to remove extremist material from the web and should do more to help authorities tackle terrorism.

Prisons need to be more alive to potential extremism among inmates.

The Home Office has failed to hand over key documents relating to the asylum seeker who set off a bomb in Parsons Green.

Chances to catch the Manchester bomber were missed.

Delays in identifying suspects and getting foreign documents translated can hamper investigations.

Manchester bomber Salman Abedi, 22, visited a category A extremist inmate in prison - previously identified as ISIS recruiter Abdalraouf Abdallah - but 'no follow up action was taken', the report found.

The report found police had not alerted prison authorities about the risk posed by Abdallah, meaning his visitors were not security checked.

Counter-terror police were also alerted to Abedi frequently travelling to Libya from 2014 onwards but he was not made the subject of travel restrictions or monitoring.

Abedi's case was also flagged for review, but was not re-examined before he slaughtered parents and children at the Ariana Grande concert, today's report found.

Dan Hett (left), whose brother Martyn (right) died in the Manchester attack, called for tougher action against social media companies who help extremists spread hate

After the report was published, Martin Hibbert, who was injured in the blast, tweeted: 'It is heartbreaking and very frustrating when you see what [Abedi] was doing and where he was travelling to weeks before the bomb.

'We've known this for a while now and it's good to see people now admitting failings and mistakes were made.'

Robby Potter, who narrowly avoided death when shrapnel from the bomb struck his heart, told the BBC he was considering legal action against MI5, adding: 'I'd have more respect for them if they had said immediately after "we made a mistake - we underestimated this man".

Robby Potter (left) is pictured with his wife Leonora Ogerio. The couple were waiting for their children after the concert. Mr Potter was just a millimetre from death after a nut was shot through his heart, while Miss Ogerio's legs were fractured in the explosion

'I love my country but I was let down. This could have been stopped, and we're finding out now that it should have been stopped.'

ISC chairman Dominic Grieve said: 'What we can say is that there were a number of failures in the handling of Salman Abedi's case and, while it is impossible to say whether these would have prevented the devastating attack, we have concluded that, as a result of the failings, potential opportunities to prevent it were missed.'

Mr Grieve noted that both MI5 and counter-terror police have been 'thorough in their desire to learn from past mistakes', adding: 'The lessons from last year's tragic events must now result in real action.'

MI5 has accepted it 'moved too slowly' to review Abedi's case after an investigation into him was dropped in 2014.

Khalid Masood (pictured, left) murdered Pc Keith Palmer (right) in last year's Westminster terror attack. He was known to MI5 before the attack

Masood is shot outside Parliament. The report found it took weeks to identify him after his phone number was handed to authorities

The terrorist regularly went to see Abdalraouf Abdallah, who was jailed after trying to help other Manchester-based fanatics join extremists in Syria.

Despite this, Abedi was not considered for a referral to the Prevent anti-terror scheme, MPs revealed.

Thirty-six people died in five terror attacks on UK soil last year, with four striking the capital, prompting today's Parliamentary report.

MPs hit out at 'fundamental failings' in the handling of the case of Parsons Green bomber Ahmed Hassan, and delays by the Home Office in handing over information, prompting a separate review in his case.

Officers shot the attackers dead during their rampage through London Bridge and Borough Market in south-east London last year

One of the three men who carried out the London Bridge attacks had been under investigation

On the Parsons Green attack, committee chair Mr Grieve said: 'There were fundamental failings around this young man's arrival in the UK and how he was handled thereafter.

'There was clear evidence that he had been with IS, that he had witnessed or participated in acts of violence. His behaviour showed signs if disturbance.'

The committee also made broader recommendations in relation to all five terror attacks last year.

MPs castigated internet firms for failing to tackle the scourge of extremism online and call on large firms to boycott advertising with them until more is done to take down hate speech and bomb recipes.

The report states: 'We recommend that pressure is out on Communications Service Providers (CSPs) by the business community, following the example of companies such as Unilever.

'We strongly consider that action which affects CSPs' profits will hit home harder than an appeal to them to 'do the right thing' and could force them to take action on this crucial issue.'

Unemployed father-of-four Darren Osborne from Cardiff (left) killed Makram Ali, 51, (right) in the Finsbury Park Mosque attack

Fury over 'fundamental failings' in the handling of the Parsons Green bomber Ahmed Hassan (right) have led MPs to order a separate report after he left an IED (left) on a Tube train

The reports also criticises authorities to failing to learn lessons from the 7/7 attacks and the killing of Lee Rigby, adding: 'The lessons from last year's tragic events must now result in real action.'

In response to the report, Met Police Commissioner Cressida Dick told LBC radio: 'I am very confident that we actually have implemented a huge number of changes since last year.

'I am equally confident that in this country, thanks to persistent investment and learning over the last many many years, we have a very powerful counter terrorist machine, which includes the police and the government, and the security services, and we will strive with every sinew to improve and improve.'

How the five terror attacks which claimed 36 lives last year exposed blindspots for police and security services

Westminster: Criminal converted to Islam in prison didn't meet threshold for re-investigation Khalid Masood was radicalised in prison Khalid Masood, 52, an Islamic convert living in Birmingham, drove car over Westminster Bridge on March 22 2017, mounted the pavement and killed five pedestrians before entering the gates of parliament and fatally stabbing PC Keith Palmer. He had an extensive criminal history dating back to 1978, with his most notable offences for violent crimes between 2000 and 2003. Between 2004 and 2013, Masood was known to MI5 due to his participation in extremist circles and he was actively investigated by MI5 between 2010 and 2012. He was assessed to be a distributor of extremist material and possibly involved in facilitating the travel of individuals of concern to the tribal areas of Pakistan. During the period between 2012 and 2016, MI5 observed 'intermittent contact' between Masood and other individuals of interest but nothing that met the threshold for re-investigation. The committee said that MI5's failure 'fully to take into account the cumulative effect of individuals appearing on the periphery of numerous investigations' appeared to be relevant Masood's case, just as it was with Salman Abedi, the Manchester bomber. Victims (left to right) Pc Keith Palmer, Aysha Frade, Leslie Rhodes, Andreea Cristea and Kurt Cochran They also noted that prisoners who convert to Islam in jail, like Masood, are around four times more likely to be convicted of an Islamist-related offence than the general British Muslim population. Counter-Terrorism Policing accepted: 'The data would tend to suggest, that people who have converted are more vulnerable to radicalisation and potentially even – I don't think there is a scientific way of saying this – but potentially not just being radicalised but becoming violent.' The ISC said: 'Prison officers must be trained to identify instances where someone has converted following association with extremists, to assess whether that conversion is therefore part of a positive journey or a negative one for an individual, and to be able to take action in the latter case.' Advertisement

London Bridge: Investigation into one attacker was suspended while intel on Italian killer took 49 days to be translated Khuram Butt, Rachid Redouane and Youssef Zaghba used a van to run over pedestrians on London Bridge on June 3 2017 before launching a knife attack in Borough Market, killing eight people. Despite the attack on Westminster Bridge in March 2017, the report noted that 'hostile mitigation barriers' were not installed on the eight Thames bridges in central London until after the London Bridge attack three months later. Remarkably, Counter-Terrorism Policing told the committee: 'Westminster Bridge, that was not considered an attack on a bridge, it was just one of the crowded places in an attack on parliament.' Khuram Butt, Rachid Redouane and Youssef Zaghba killed eight people in last year's attack on London Bridge Butt first came to the attention of authorities in relation to investigations into the banned extremist group al-Muhajiroun (ALM) and he was actively investigated by MI5 between mid-2015 and 2017 following reports of 'aspirations' to conduct an attack in the UK. The investigation into Butt, 27, from Barking, East London, remained open at the time of the attack, but MI5 never detected any signs of attack planning. 'Operation Begonia' included a 'significant amount of coverage' the ISC said, but it was suspended twice – from February to April 2016 and from March to May 2017 – due to competing pressures from higher- priority investigations. It was downgraded in September 2016 and on May 5 2017, MI5 were minded to close the investigation, but decided first to increase coverage in order to ensure they had a full picture of the risk posed by Butt. Discussions were continuing about how he would be managed and what ongoing investigative actions were required at the time the attack took place. MI5 had received one piece of intelligence on Zaghba in June 2016 from Italian liaison regarding Zaghba's attempted travel from Italy to Istanbul in March 2016. Victims (top row left to right) Christine Archibald, James McMullan, Alexandre Pigeard, Sebastien Belanger, (bottom row left to right) Kirsty Boden, Sara Zelenak, Xavier Thomas and Ignacio Echeverria The Italian authorities assessed that he wanted to travel onwards to Syria and requested traces on Zaghba from MI5. Zaghba had attempted to fly from Marconi airport, Bologna, to Istanbul on March 15, telling he was going to Istanbul 'to be a terrorist' before immediately correcting himself to 'tourist'. MI6 was informed on April 15 and traces were requested for any contacts he had in the UK with individuals linked to Islamist extremism. The note was 'triaged' but was not translated by MI6 until 49 days later and, as a result, MI5 did not receive the note until six days after that. The committee heard there was no record of an MI5 response, and the note was not filed in MI5's corporate system. The report said that 'regardless of operational demands, an eight-week delay between the receipt of a trace request from a partner agency and onward dissemination is far too long.' MI5 had also received a number of strands of intelligence regarding a Moroccan male named Rashid, who they assessed to be a social associate of Butt, now thought to be Redouane. Advertisement

Manchester: Suicide bomber visited extremist in jail and went to Libya unchallenged Salman Abedi, seen on CCTV a few days before the attack Salman Abedi, 22, from Manchester, detonated a homemade bomb in the foyer of Manchester Arena on May 22 2017 at the end of a concert by Ariana Grande. The report criticised how he was able to visit a prisoner who was a known extremist and travel back and forth to Libya before the attack. Abedi was briefly investigated by MI5 in 2014 when he was suspected of being an individual who had been observed acting suspiciously alongside an existing Subject of Interest (SOI). The investigation into Abedi ended due to his limited contact with the SOI and because he was assessed as 'not identical with the individual mentioned in the original reporting'. Between 2015 and 2017, the authorities received further reporting about Abedi's activities and an internal MI5 process raised his case in March 2017 for potential further investigations. However final decisions had not taken place by the time he launched his attack. Dominic Grieve, chairman of the ISC said: 'There were a number of failures in the handling of Salman Abedi's case and while it is impossible to say whether these would have prevented the devastating attack on 22 May, we have concluded that, as a result of the failings, potential opportunities to prevent it were missed.' Abedi's victims were youngsters who had gone to a pop concert and never came home Advertisement

Finsbury Park: Loner had no known links to far-right groups Darren Osbourne was not known to security services Darren Osbourne, 48, from Cardiff drove a vehicle into a group of people gathered near a mosque in Finsbury Park in north London on June 19 2017, killing Makram Ali. He was said to have had an extensive criminal history dating back to 1984, including 33 convictions for 102 offences ranging from offences against the person to drugs and theft. The ISC report said the post-attack investigation indicated that Osborne acted alone. He had not been investigated by MI5 or Counter-Terrorism Police before launching his attack and was 'not known to be a member of, or have links to, any extremist right-wing groups.' Advertisement