British detectives have questioned for the first time a man held in Italy on suspicion of trying to blow up a Tube train in London on 21 July.
Hussain Osman faces an extradition hearing on 17 August
Hussain Osman, 27, also known as Hamdi Issac, is facing extradition to the UK.
An inquiry is also under way into whether he should face international terrorism charges in Italy.
Scotland Yard anti-terror officers are expected to question him for at least two days, after more than a week of negotiations with officials in Rome.
His Italian lawyer, Antonietta Sonnessa, said he had told them he "had no intention to kill anyone".
Mr Osman fled to Italy by train after allegedly being seen at the scene of the failed bombing at Shepherd's Bush underground station.
He was being questioned by UK police at Rome's Regina Coeli (Queen of Heaven) prison.
Outside the prison, about three hours after the British officers arrived, Ms Sonnessa said Mr Osman had told them "that as far as he knew the contents of the bag were not aimed at harming anyone, including himself".
"It was a demonstrative act," she said he had told officers.
"There were a few nails, but the explosives were not meant to harm, just to make noise."
Ms Sonnessa added she was looking forward to seeing the British police report on the explosive Mr Osman was alleged to be carrying when he was spotted leaving Shepherd's Bush Tube station.
The detectives had questioned him in English and he had replied in Italian, with an Italian magistrate translating, Ms Sonnessa said.
They had also shown Mr Osman photographs, she added.
The judge leading the Italian investigation and Rome's chief prosecutor was also present at the interview.
Mr Osman has been held in isolation at the jail since he was arrested at an apartment belonging to one of his brothers on the southern outskirts of the city on 29 July.
21 JULY PLOT ACCUSED
Ibrahim Muktar Said, aged 27
Ramzi Mohamed, aged 23
Yassin Hassan Omar, aged 24
Manfo Kwaku Asiedu, aged 32
According to legal sources, Ethiopian-born Mr Osman, who has British citizenship, has the right to refuse to answer questions put to him by the British interrogators.
Britain's extradition request will be considered at a hearing in Rome next week. Mr Osman is also being investigated by the Italian authorities in connection with possible terrorism charges he may face in Italy.
BBC Rome correspondent David Willey says the extradition process is expected to take some weeks, if not months.
He said: "The Italian judiciary have got some charges which they may be bringing against the suspect for international terrorism committed on Italian territory and of course that will have precedence over anything the British police do."
He added that, as Mr Osman had been arrested under a European arrest warrant, the extradition process should not take more than three months.
Bomb suspects Ibrahim Muktar Said, 27, Yassin Hassan Omar, 24, and Ramzi Mohamed, 23, appeared before magistrates on Bow Street magistrates sitting at Belmarsh high security prison in south-east London, on Monday.
They are charged with attempted murder and possessing explosives.
One charge faced by Manfo Kwaku Asiedu, 32, relates to an unexploded device found two days after the bomb attempts.
The four men - who are also charged with conspiracy to murder - were remanded in custody for three months and will next appear in court on 14 November.
The failed 21 July attacks took place two weeks to the day after four suicide bombers killed 52 passengers on the London transport network.