Detectives are questioning two men over the failed bomb attacks in London on 21 July, who were arrested in armed raids in the capital on Friday.

A third suspect detained by Italian police will face an extradition hearing in Rome on Saturday. A fourth man was held in Birmingham on Wednesday.

CCTV images of the four were shown around the world after the attacks on three London Tubes and a bus.

A fifth man is being questioned over a device found in west London last week.

Police are urging the public to remain vigilant to the threat of more attacks.

West London streets were cordoned off on Friday as dozens of police, many armed and some wearing gas masks, surrounded properties.

Specialist tactics

A flat in Dalgarno Gardens, on the Peabody estate in North Kensington, was raided and two men eventually surrendered to armed police.

Muktar Said Ibrahim, 27, is the number 26 bus bomb suspect and Ramzi Mohammed is wanted over the failed attempt to bomb a Tube train near Oval station.

Deputy Assistant Commissioner Peter Clarke, of the Metropolitan Police, said "specialist tactics" were used after the men had failed to comply with police requests to surrender.

In nearby Notting Hill another man was arrested after police stormed a flat on Tavistock Crescent.

The Press Association has named the man as Wahbi Mohammed, 23, brother of Ramzi.

It is thought detectives will question him over a device found on Little Wormwood Scrubs near the Peabody estate last Saturday.

Two women were also arrested under the Terrorism Act on Friday at London Liverpool Street train station.

Italian arrest

Meanwhile in Rome a UK citizen named as Osman Hussain, 27, is being questioned over the bomb attempt at Shepherd's Bush station.

Scotland Yard said the suspect is expected to face a fast-track extradition back to the UK under the new European Arrest Warrant, legislation which only came into effect in Italy last Thursday.

Italian investigators said Mr Hussain's real name may be Hamdi Isaac and he is either Eritrean or Ethiopian.

It is believed he was brought up in Italy, where his family sought asylum from Somalia.

He had been staying with his brother, who was also arrested, Italian officials said.

Police tracked him to the Italian capital by monitoring his mobile phone calls. Moves are under way to extradite him to Britain.

Scotland Yard described Friday as their "best day yet" in the hunt for the 21 July bombers.

But Mr Clarke insisted the public "must not be complacent" in assuming the threat of attacks had disappeared.

"The threat remains and is very real," he told reporters.

Police are making clear the period of intense security activity is far from over.

BBC security correspondent Frank Gardner said the police's main priority is to establish if there were any further bomb plots.

Then they will begin to look for international links the suspected bombers may have had, he said.

PHOTO CAPTION

Italian scientific police inspect a Rome apartment following the arrest of Somali-born Briton Osman Hussain. (AFP)