The London bombing suspect arrested in Rome last week was more likely part of a loose group of amateurs than an Islamic radical ring, Italian police said Monday as Britain sought his extradition.

Investigators in Rome said Issac Hamdi, also known as Osman Hussain, did not fit the profile of a member of a large and organized insurgent network.

"Concerning Hamdi, we are presented with details that very likely appear more part of an impromptu group than a structured organization that had broader terrorist projects," said Carlo De Stefano, head of Italy's anti-terrorism police forces.

De Stefano told reporters that Hamdi was cooperating with authorities. Two of his brothers have been arrested in Italy on lesser charges, including possession of false documents.

British police want to question Hamdi as soon as possible. They believe that all four men they were seeking in the failed July 21 bombings on three subway trains and a bus have now been captured.

The attempted bombings came two weeks after four young British Muslim men, according to police, killed themselves and 52 other people with bombs, also on three underground trains and a bus.

Italian police said Hamdi was from Ethiopia but lived in Italy from 1991 to 1996. He obtained fake Somali documents and secured British citizenship using the false name Osman Hussein.

British detectives are questioning 20 people arrested as part of the probe into the attacks, the biggest operation for London's police since World War II. Two were arrested Monday. Police continue to search the country for anyone who might have helped the bombers.

Police have said they will take race into account when deciding which people to stop and search, despite fears among some Muslims that this could anger members of their community. Peter Hain, a cabinet minister, insisted that the government wanted to avoid provoking any backlash.

"We can't have that. At the same time, we have to be clear we are dealing with an entirely new phenomenon of worldwide suicide terrorism and you can't take any chances," he told BBC radio.

On Monday, an Italian court confirmed the preventive arrest of Hamdi on accusations of international terrorism and false documents. His lawyer, Antonietta Sonnessa, said this could soon lead to formal charges and a trial, likely precluding extradition to Britain.

"At this point in Italy, there is evidence of guilt against the defendant in Italy, and so the proceedings are in progress in Italy," she said. "I'm not saying it can be taken for granted that extradition won't happen. But of course one thing excludes the other, logically."

Sonnessa said Hamdi denied any ties to al Qaeda, or any other militant Islamic network. He also denied ties to those who led the July 7 bombings but admitted to carrying explosives on July 21, she said.

[The Associated Press reported that De Stefano said Italian authorities' hunt for Hamdi began on July 26, when British officials told Italian police that a suspect in the July 21 attacks had fled Britain and in the past had made calls to Italian phone numbers.

[British police also said the suspect called Saudi Arabia, apparently to get his brother's number in Rome.

[Police homed in on Hamdi's cell phone, locating him Thursday after discovering that he had replaced the phone's British removable "SIM" card -- which stores an individual's phone number and other data -- with an Italian one.

[On Friday, the day of the arrest, police recorded conversations in which Hamdi talked in an Ethiopian dialect, which helped confirm his identity. Italian police were also aided in identifying Hamdi in part by a wound on his right leg, which British police said he suffered as he tried to leap a subway station barrier after the failed attack at the Shepherd's Bush subway station.

[In London, police investigating the bombings said Monday they had arrested two men during raids in south London. A spokeswoman for the Metropolitan Police said the men had been arrested "on suspicion of the commission, preparation or instigation of acts of terrorism."]