Bin Laden 'ordered the attack on the US embassy'
Djamel Beghal, 35, was extradited on Sunday from the United Arab Emirates in connection with the alleged plot.
A French radio report said Mr Beghal had spoken in detail about being recruited by Bin Laden, the prime suspect for the 11 September attacks on the US.
Formal investigation
"The key point is that he has contested being commissioned by anybody to organise, prepare and carry out terrorist acts, notably against US interests in Paris," said the lawyer.
Mr Beghal was placed under formal investigation on Monday evening, a step short of being officially charged, for alleged "criminal association in connection with a terrorist enterprise".
Europe-1 Radio reported on Tuesday that it had seen the document outlining Mr Beghal's confession, in which he spoke of being recruited in Afghanistan by Bin Laden's deputy, Abu Zubaydah, for a suicide mission against the embassy.
In the document, the radio station reported, Mr Beghal said that he met Abu Zubaydah after being summoned to the Bin Laden's house during a visit to Kandahar in Afghanistan.
Abu Zubaydah asked him if he was ready for action and told him the plan consisted of blowing up the US embassy in France, the document is reported to say.
The radio station said the plan, to be carried out some time this year, was to blow up the embassy with a minivan packed with explosives.
Gifts
Mr Beghal reportedly said his role was to observe, collect information and assess the extent of the surveillance in place around the embassy.
He was reported to have been given three gifts by Abu Zubaydah who said they were from Bin Laden.
Europe-1 reported that UAE judges and police resorted to the "trick" of using religious leaders to coax Beghal into confessing instead of subjecting him to police questioning, as Islamist militants normally refuse to answer questions under interrogation.
Mr Beghal had been held in the UAE since July after being arrested with a fake passport on his way back from Afghanistan.
He was the second person in as many days to be extradited to France in connection with the alleged plot.
Kamel Daoudi, 27, also a French-Algerian, was extradited from Britain on Saturday.