The allegation has been denied by Mr Kohl, who has so far only admitted receiving about $1m in secret donations.

Mr Kohl's spokesman described the allegations as part of a character assassination.

ARD television reported that Mr Mitterrand arranged payments of about 30m marks ($15.7m) to Mr Kohl's Christian Democratic Union (CDU) through a French oil company.

The left-wing French Government and the conservative German administration were close allies in the European Union during Mr Kohl's time in power.

Missing files

The German TV report said the money was transferred as part of alleged bribes totalling 85m marks ($44m) paid by France's Elf-Aquitaine for its 1992 purchase of the former East German Leuna refinery.

The alleged payments are already being investigated by prosecutors in Switzerland and France, but files on the sale - which were kept in the German Chancellor's office - have gone missing.

BBC Berlin correspondent Caroline Wyatt says there is a deepening impression of a massive cover-up at the highest levels of the former government of Helmut Kohl.

Auditors fail to trace donations

In an separate development, auditors investigating the finances of the CDU say they have failed to trace the origin of nearly $6m paid to the party in secret campaign donations.

Mr Kohl has consistently refused to name the donors, and is facing both criminal and parliamentary investigations into possible breaches of party financing laws.

Leaders of the CDU met late into Sunday night to discuss the auditors' report, but they made no announcement after the meeting.

They are due to hold a news conference on Monday (1300GMT).

Hoax statement

There was further confusion on Sunday, when a statement was released saying that Mr Kohl was about to name the mystery backers who bankrolled his party with secret donations.

The facsimile, which was written on Mr Kohl's headed notepaper, was sent out to media organisations from the CDU's parliamentary office in Berlin.

It was quickly dismissed as a hoax by CDU officials, who said it was a fake probably intended to increase the pressure on Mr Kohl to identify the donors.

The former chancellor's repeated refusal to do so has fuelled speculation that the money was used to buy political favours.

But Mr Kohl says he is simply honouring his promise to the donors that their identity would not be revealed.

The party funding scandal blew up last month when Mr Kohl admitted he had accepted two million marks ($1m) in secret funds from anonymous benefactors.