One of the 21 July London bombing suspects has been charged under Italian anti-terrorism laws, his lawyer says.
Hussain Osman is being linked to the Shepherd's Bush attack
Antonietta Sonnessa said Hussain Osman, 27, was charged with association with the aim of international terrorism and with possessing false documents.
The move allows the authorities to continue holding Mr Osman - also known as Hamdi Issac - and is separate from Britain's attempt to extradite him.
Earlier, Italian police said a mobile phone helped them catch Mr Osman.
Carlo de Stefano, head of Rome's anti-terrorism police, said Mr Osman had been in constant contact with family members in Italy as he travelled from London.
SUSPECTED BOMBERS ARRESTED
1: Yassin Hassan Omar, 24, wanted over bomb attempt on a Tube near Warren Street, arrested in Birmingham
2: Ibrahim Muktar Said, 27, suspected of attempting to bomb a No 26 bus in Shoreditch, arrested in North Kensington, London
3: Ramzi Mohamed, 23, wanted over failed attempt to bomb a Tube near Oval, arrested in North Kensington, London
4. Hussain Osman, 27 (also known as Hamdi Issac) wanted over the Shepherd's Bush attack, arrested in Rome
Police in the UK claim Mr Osman ran from Shepherd's Bush station in west London on 21 July - after he had allegedly attempted to bomb a train.
They are maintaining a high-profile security operation in case of another attack.
Two of Mr Osman's brothers have also been arrested and questioned by police in Italy, but Mr de Stefano said it appeared there were no links to larger international terrorist organisations.
He said Italian police had enjoyed close co-operation with the Metropolitan Police during the inquiry and were still receiving information about the suspects.
He added that Mr Osman left Italy in 1996 and arrived in the UK, where he told authorities he was Somali in order to be naturalised as a British citizen.
He was arrested in Rome on Friday using a European arrest warrant, one day after the legislation had been introduced in Italy.
His is the first case in which Italy has been asked to hand over a terrorist suspect to another EU country under the new rules.
Italian police were able to identify him after the British police described an injury to his foot.
Italian authorities questioned Mr Osman, and his brother Ramzi, for four hours before charging them with using false passports.
They are accused of travelling from London to Rome on the passport of another brother, who is based in London.
Mr Osman is believed to have left London Waterloo on a Eurostar train on 26 July, travelling to Paris and Milan before arriving in Rome.
On Sunday, Leader of the Commons Geoff Hoon said ministers were to investigate how he was able to leave the UK after the attacks.
He said extra passport checks for those leaving the country were being considered.
France could also tighten up its borders. Transport Minister Dominique Perben said on Monday the suspect's entry into France "requires us to think about our border surveillance system".
As the British police investigation into the failed bombings continues, six men and a woman remain in custody after being arrested during police raids in Brighton on Sunday morning.
They are being held under the Terrorism Act on suspicion of the commission, preparation or instigation of acts of terrorism, or harbouring fugitives.
Since the arrests on Friday of those suspected of carrying out the failed bombings, police are focusing on finding those who helped plan and finance the attacks, as well as those of 7 July.
But a police spokeswoman on Sunday played down claims officers were hunting a third cell poised to strike.
She said: "We are searching for other people in connection with this ongoing inquiry. We have never spoken about a third cell.
"There were quite a few other people involved in the incidents of the 7th and the 21st. It's extremely likely there will be other people involved in harbouring, financing and making the devices."
Police have also been allowed extra time to question Yasin Hassan Omar, the man suspected to trying to blow up a train between Oxford Circus and Warren Street.
He can be questioned until Wednesday. He was arrested in Birmingham on 27 July.
Two other suspected bombers, Ibrahim Muktar Said, 27, and Ramzi Mohamed, remain in custody after being arrested during an armed raid in London on Friday.
Suspects can be held for a maximum of 14 days under the anti-terror laws before they must be charged or released.