Nine men were arrested in armed raids in south London before dawn today, as police mounted their biggest ever security operation on London transport exactly a week after the attempted July 21 terror attack on three Tube trains and a bus.

Six men - variously said by neighbours to be either Pakistanis or Algerians - were arrested after a struggle at a house in Garratt Terrace, Tooting, and a further three men - said by a shopowner to be Turkish restaurant workers - were arrested in flats over a kebab shop on Tooting High St. Both raids began at 04.30 BST, and the men were marched quickly up the road to waiting police vans.

Jennifer Brooker, 58, who lives opposite 5 Garratt Terrace, said she saw about 13 people being taken out of the property, three of them women, including a Chinese woman. She said she also saw an old woman with a walking stick who had to be helped along the road. About nine or ten men were removed.

She said: "All of them had white cable around their wrists and they were led out by armed police. A little old lady was among them with a walking stick, she had to be helped along the road.

"I heard one of the officers shouting ’Drop your trousers to your ankles’. One of the men brought out was in his boxer shorts, some of them had no shoes on, some of them were wearing nothing on top and some were wearing long white robes. It was just scary seeing it all."

Subash Patel, a driver with a nearby taxi company, said that up to 15 people lived in the house, mainly Pakistani men. A neighbour maintained that at least two French-speaking Algerians lived there, including a balding man aged about 45 and a 65-year-old.

Ahmet Ali, the owner of the kebab shop, said that three members of his staff were arrested, aged about 26, 30 and 40 to 41. He said the oldest man had worked for him for eight years. The other two had started about two months ago.

Mr Ali’s wife Maria said they had been running the shop for 13 years and the staff lived in the flats above the shop. She said: "I don’t think the staff had anything to do with this. This has all been a shock."

All nine were arrested under the Terrorism Act and have been taken to a Central London police station for questioning. No bomb disposal unit was called in and none of the three bombers still missing since the abortive July 21 terror attacks is thought to be among the arrested men. A Scotland Yard spokesman said that local residents had not been evacuated and added: "We don't think it's one of our principal suspects."

Specialist interrogators will continue to question Yasin Hassan Omar today, the only one of the suspected July 21 bombers to be caught by police so far. Omar is being held at Paddington Green high security police station in Central London, where he was taken after being shot with a stun gun by anti-terrorist officers in Birmingham yesterday during a dawn raid.

As London remained on maximum terror alert, seven days after the attempted explosions and 21 days after the devastating London bombs which killed 52 commuters and four bombers, the Commissioner of the Metropolitan Police warned that other terrorist cells could be at large and determined to launch a third attack.

Sir Ian Blair told a police authority meeting: "I’m confident we will identify the bombers responsible and those who backed them. But it does remain possible. We are in a sombre moment and it does remain possible that those at large will strike again.

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