An aide to former French Interior Minister Charles Pasqua has been questioned in connection with the UN's Iraq oil-for-food programme.
There are many investigations into the oil-for-food programme
Bernard Guillet appeared before a judge investigating allegations of corruption regarding the re-sale of Iraqi oil.
Mr Pasqua - now a French senator - has denied having anything to do with the scandal that has rocked the UN.
"I never received anything. I never took part in any sales," Mr Pasqua told the Associated Press news agency.
The $60bn (£32bn) oil-for-food programme allowed Saddam Hussein's Iraq to sell oil in order to buy civilian goods - including medicine - and thereby ease the impact of UN sanctions imposed after Iraq's 1990 invasion of Kuwait.
Bernard Guillet was first held on Tuesday as part of a French investigation into suspected secret payments that officials are alleged to have received to favour French companies in the UN-run programme.
He was placed under judicial investigation - a step short of full charges.
Mr Pasqua told the AP the investigation "does not concern me".
He said claims - made in an Iraqi newspaper - that he may have been involved were "ridiculous".
"I have said and thus I confirm that I have strictly nothing to do with this affair. I never received anything. I never took part in any sales," he told AP.
Last year, the US-led Iraqi Survey Group that was looking for weapons of mass destruction in Iraq, listed Mr Pasqua among officials described as "known oil voucher recipients".
The ISG said that at least some of the vouchers - which permitted recipients to purchase varying amounts of oil at a profit - were issued legitimately through the oil-for-food programme. But it stressed that receipt of a voucher did not mean it was ever actually cashed in.
The UN oil-for-food programme has been the subject of several corruption investigations.
UN Secretary General Kofi Annan has been criticised over his son's work with the programme.
A US and a Bulgarian have been arrested in the US and indicted for bribery.
Briton John Irving has also been accused. He denies any involvement.
Mr Annan has criticised the US and the UK, suggesting the two had inadequately policed UN sanctions against Iraq, enabling the regime to earn huge amounts in illegal deals.
Both countries have rejected the criticism.