Former French Interior Minister Charles Pasqua says legal proceedings against him have begun in connection with the Iraqi oil-for-food scandal.
A US Senate report published last year contained the accusations
He has been placed under judicial investigation, a step that could lead to formal charges.
Mr Pasqua, 78, is suspected of accepting allocations of oil from the government of Saddam Hussein.
Mr Pasqua has denied the allegations, which he had said were part of a US bid to discredit President Jacques Chirac.
He said his lawyers would immediately contest the accusations.
Mr Pasqua told AFP news agency that he had "never touched a single oil voucher".
A senator belonging to France's governing UMP party, he was interior minister in the 1980s and 1990s.
The UN's oil-for-food scheme was worth $60 billion
The oil-for-food programme was set up to allow Iraq to buy food, medicine and other humanitarian supplies with the proceeds of regulated oil sales, without breaking the sanctions imposed on it after its 1990 invasion of Kuwait.
It was established in 1996 and aimed to relieve the suffering of ordinary Iraqis under the sanctions.
The programme ended in 2003 after the US-led invasion of Iraq and the overthrow of Saddam Hussein.
The scandal emerged in early 2004, after an Iraqi newspaper published a list of people - including politicians and UN officials - it alleged may have profited from the illicit sale of Iraqi oil during the scheme.
The UN set up an inquiry into the allegations in April 2004. It has come under fire as the organisation responsible for administering the programme.