About 6,000 police are positioned around London's transit system this week in a show of force aimed at deterring more bomb attacks. Meanwhile, over the weekend, investigators made more arrests in the July 21 failed attacks.

There are fears that a third wave of attacks could happen this week, based on information that may have been gleaned from police interrogations of suspects rounded up so far.

British police have remained mum on what they've learned from the 23 people arrested so far in the attacks.

However, Italian police released more details Monday about the man nabbed in Rome in connection with the July 21 failed attacks on London's transit system.

The Ethiopian-born British citizen Osman Hussain, also known as Hamdi Issac, has a brother living in Canada, according to Italian police.

Police say Abdulahai Issac, one of the suspect's four brothers, traveled from Italy to Canada in 1996. He was reportedly given landed immigrant status as a political refugee.

Officials did not say whether Abdulahai Issac was under investigation.

Two other brothers are already in police custody -- Remzi Issac and Fati Issac. It was at Remzi's Rome apartment where Osman Hussain was nabbed on Friday.

Hussain, 27, is suspected of trying to bomb the Shepherd's Bush subway station in west London.

He was charged Monday under Italy's anti-terrorism laws with association with the aim of international terrorism and with possessing false documents, said Antonietta Sonnessa, his lawyer.

Britain has asked that the suspect be extradited. Sonnessa said nothing had been decided Monday concerning that request. However, Italian police say they don't believe it will be long before Hussain is taken back to the U.K.

New details released

Police said Issac changed his name to Osman Hussain in 1996, and claimed that he was from Somalia, not Ethiopia, when he left Rome for the United Kingdom.

"He falsely declared he was a Somali citizen to obtain the status of a political refugee and get economic assistance more easily," said Carlo de Stefano, the head of Italy's anti-terrorism police.

De Stefano also said the suspect seems to be part of "an impromptu group rather than part of a structured group which is operating on an international scale."

Police described in detail how they tracked him down by monitoring his cell phone calls.

Italian police began investigating when their British counterparts said one of the suspects in the July 21 attempted bombings had fled Britain, and had made calls to Italian telephones in the past.

Police tracked him down in Rome after discovering he had replaced a British phone card with an Italian one.

A wound on his right leg confirmed to police he was the man they were looking for. British police claim Hussain suffered the injury while trying to flee the scene of the attempted bombing on a London subway station.

Show of force

Officers wearing yellow neon jackets flooded the transit system in London on Monday in a show of force against would-be attackers.

Meanwhile, police continue to interrogate suspects. Two people were arrested Monday, in addition to the seven taken into custody in Brighton Sunday.

The Times of London cites senior police officers as saying there was specific intelligence that another wave of attacks was scheduled for last Thursday.

The third cell members are supposedly independent of the July 7 and 21 groups but have associations with some people who have been arrested in the anti-terror sweeps.

The Guardian newspaper, however, reported Monday there was no specific intelligence indicating an attack by a "third cell" was imminent.

Police believe they have arrested all the failed July 21 bombers, whose explosives only partially detonated.

The July 7 attacks on three subway stations and a double-decker bus killed 56 people, including the four bombers. Police say those four attackers are all dead.