Police smashed a suspected Islamist terror plot to attack London after four men were held by heavily-armed officers.

The Met acted on intelligence that the men may have had access to firearms, prompting fears of an attack similar to the Kenyan mall atrocity.

Two men aged 25 were arrested in a “hard stop” in Mansell Street near Tower Bridge last night after officers blew out the tyres of their car with shotgun rounds and rammed the vehicle. One man, aged 29, was held at his home in Peckham after a stake-out by undercover officers.

Police also seized a 28-year-old man outside an Iranian restaurant in Westbourne Grove. Around eight police cars surrounded the Alounak restaurant as the suspect came out.

Toby Lewis, 26, a waiter at Nando’s in Westbourne Grove, said: “One guy had been pushed against the wall of Planet Organic and you just had cops all around him, holding him there. They were shouting at him. No one in the restaurant was allowed to come for about an hour.”

George Paul, 30, lives opposite the scene of the Westbourne Grove arrest said: “I saw three policemen holding down a man on the floor. They were struggling with him for three or four minutes and I heard him shout, ‘Please don’t break my arm’. ”

Ramin Massodi, 27, who was working in Alounak, said: “I saw three police officers on top of a man. They had guns in their holsters.”

Neighbours at the flat in Peckham Hill Street said officers arrived at around 7pm. A neighbour said: “A young guy who looked Indian was taken away.”

Another said: “We are very shocked by all this. There were undercover police parked outside then a van came and they piled in. It is all quite scary.”

Witnesses in a block of flats overlooking Mansell Street in Aldgate told how police rammed a car before running out into the busy road to stop the suspects. They said there were two to three police cars on the main road.

One resident said: “The fire brigade was here, then there were people running out with torches. One of my neighbours said police rammed the car and then jumped out.”

The men are understood to have been under surveillance by police and MI5 for some time. Senior officers ordered the simultaneous arrests in the interests of public safety.

The suspects are understood to be different nationalities, though at least one is British. They were held in co-ordinated raids in what the Met described as a “pre-planned, intelligence led operation.” They were being questioned at a south London police station today on suspicion of the commission, preparation or instigation of acts of terrorism. Officers were searching six addresses across London as well as two cars linked to the suspects.

The threat of an attack in London by several gunmen such as in Mumbai in 2008 or Nairobi last month is the biggest fear of anti-terror chiefs.

Last week Andrew Parker, the director general of MI5, warned that Islamist extremists in the UK see the British public as a legitimate target for attacks. A Met spokeswoman said: “Public safety remains our overriding concern.”