A British medical student suspected of plotting with Islamic State announced ‘I smell war’ just hours before he was arrested.

Tarik Hassane, 21, known to friends as ‘The Surgeon’, was being questioned last night over allegations he wanted to bring terror to the streets of Britain.

He was Tasered by armed police who stormed a relative’s flat where he was sleeping after flying into the country. The devout Muslim, studying in Sudan, is suspected of travelling to Syria and conspiring with the brutal terror group.

Three of his friends, all aged 20 or 21, were also held by Scotland Yard counter-terrorism officers.

Magistrates have granted police an extra five days to question four men arrested on suspicion of plotting a terrorist attack on the UK, the Met said this morning.

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Operation: Police and MI5 stormed the flat where Tarik Hassane was staying, throwing in stun grenades, before arresting a terror suspect

Officers kicked in the property's door, threw in three stun grenades and then Tasered Hassane before arresting him at 4.30am

First picture: This is Tarik Hassane, who tweeted this picture of his ID card from medical school in Sudan

Geography: Hassane's arrest was a street away from where two of the 21/7 bombers were held in 2005. There is no suggestion of any link between the two

These grabs from amateur footage taken at the scene show a police van in Dalgarno Gardens, west London

One of them, Gusai Abuzeid, 21, a student at the Greenwich School of Management and part-time Primark worker, was arrested at home in Central London. His brother said his sibling was not religious and could not be involved in an Islamist plot.

One line of inquiry is that the men were plotting a beheading to emulate hostage murderer Jihadi John.

Hassane was arrested on Tuesday on the Princess Alice Estate, West London, where two of the July 21 bombers were found nine years ago. Armed police searched flats occupied by his aunt and uncle. One witness heard ‘three bangs’ before he was dragged out. She said: ‘His face was belligerent, angry, not at all remorseful and a complete look of hate.’

Hours earlier, the suspect tweeted that he had flown into the country, adding: ‘Oi lads … I smell war.’

He has been at the University of Medical Sciences and Technology in Khartoum since September 2013.

Security services believe that he has travelled to Syria and met with hard-line militants there.

Hassane is of Moroccan and Saudi Arabian heritage and was educated at Westminster City School. Teachers made him a ‘maths ambassador’ and he wrote award-winning poetry about his passion for football.

Police are seen escorting the suspect away after he was Tasered. He was uninjured, Scotland Yard said

Raid: Counter-terrorism officers carry belongings from the flat raided where 'The Surgeon' Tarik Hassane was arrested

Police smashed down the door and threw in stun grenades as they held four young men in separate raids

Arrest: Medical student Tarik Hassane was Tasered and arrested at a flat in Princess Alice House in west London, the damaged door can be seen on the right side of the first floor

Princess Alice house on Dalgano Way in London, where officers swooped

But neighbours said he later hung around with North Africans who pushed him towards extremist views.

His family hoped he would study at prestigious King’s College London, but he failed to get the grades.

He is a prolific user of social media, where he has condemned women for wearing make-up. He posted that so many friends had died in Syria ‘there needs to be an In the Hearts of Green Birds specifically for West London’ – a reference to a Bosnian video that celebrated ‘martyrs’ with pictures of their dead bodies. He has also urged Muslims to pray for jihadi fighters.

The brother of the second suspect said a ‘police SWAT team’ smashed into their flat hours after they had watched TV terror drama Homeland.

Arrests: Scotland Yard has held four men in London over alleged terrorism offences

Adai Abuzeid said six of his family, including his grandmother and father, a refugee from Libya, were forced to the floor. He said: ‘I looked at Gusai, using my eyes to ask what was going on. He looked baffled – that’s how I know he hasn’t done anything ... He’s working hard to make something of his life. I can’t believe he’s been arrested – it doesn’t make sense.

‘If anything, he’s not really a Muslim – he doesn’t pray. He’s not political either. Our whole family is against what is going on out there.’

Mr Abuzeid said his brother had known Hassane since primary school, but they had ‘drifted apart’.

Officers said one suspect had to be shot with a Taser during the arrests, but did not require medical treatment

Last night, Scotland Yard Commissioner Sir Bernard Hogan-Howe said the ‘drumbeat around terrorism has changed’. He said: ‘We are having to be more interventionist and a lot of it is linked back to Syria and Iraq. These are arrests that in some way or other have got that sort of link.’

Whitehall officials said the move may have ‘foiled the early stages’ of a planned attack. The men, arrested under the Terrorism Act on suspicion of being involved in the commission, preparation or instigation of terrorism, can be held for 14 days.

One expert warned ‘around 1,000’ young British men have flown to Syria to fight. Raffaello Pantucci, of the Royal United Services Institute, said many are ‘excited’ by IS propaganda.

News of the raids comes after terrorist Omar Hussain, a former Morrisons worker, last week urged British Islamists to launch attacks

Former Guantanamo Bay detainee Moazzam Begg yesterday said he offered to negotiate with IS to free Alan Henning - but the foreign office turned him down. Mr Begg suggested he knew the terrorists.

In response, the Prime Minister said: 'We are very happy to work with anybody. My understanding is that Moazzam Begg did make some appeals, sadly, as we know, those appeals fell on deaf ears . . .

'But if Moazzam Begg has information to provide about who these people are, he should provide it.'

Mr Begg is a controversial figure who, until last week, was awaiting trial on seven terror charges relating to Syria. The case against him was dropped after new intelligence from MI5.