All the four failed London [Images] bombers are thought to be in custody following armed raids in the British capital and Rome on Friday.

"We have four people in custody we believe are the images we released," a police official said referring to the closed circuit television pictures of the four suspects released after the July 21 attacks.

Police arrested three men during dramatic raids on the Peabody estate in west London and in the Tavistock Road area of Notting Hill, two of whom are suspected to be the bombers.

The raids were connected to the failed bombings attempt on July 21, exactly two weeks after 56 people were killed in bombs on London's transport network.

Another suspect was arrested in Birmingham on Wednesday. In Rome, Italian police arrested another suspected bomber on Friday.

One suspect in the bombing attacks in London named Muktar Said Ibrahim was among those arrested in the British capital head of the Metropolitan Police's anti-terrorist branch Peter Clarke said in a statement.

Police said he was the man suspected of attempting to blow up the number 26 bus in Shoreditch. The second man has identified himself as Ramsi Mohammed, he said.

One of the suspected bombers Somali-born Yassin Hassan Omar, 24 is already in custody after being arrested in Birmingham earlier this week.

The fourth suspect, wanted for the attempted Shepherd's Bush Tube attack, was arrested in Rome and has been named as Somali-born UK citizen Osman Hussain.