Mr Le Pen is also accused by his opponents of misusing party funds to pay for a personal housekeeper.

Mr Megret, long regarded as Mr Le Pen's deputy and probable successor, is heading challenges within the National Front to oust Mr Le Pen.

Besieged by calls from opponents to resign, Mr Le Pen has vowed to serve out the remaining two years of his three-year term as party president.

Party reprisals

The National Front's political bureau is to hold an executive bureau meeting on 23 December to decide whether to bar Mr Megret and other rebel members of the party for good.

However, on Sunday, Mr Megret held an emergency meeting of the party's National Council, at which Mr Le Gallou said more than half the members were present and voiced their support for a special party congress next month, which Mr Le Pen opposes.

Mr Megret's backers say they have assembled more than 10,000 signatures in favour of such a meeting - well over the required 8,000.

Another of Mr Megret's supporters, Daniel Simonpieiri, said an emergency party congress called to try to unseat Mr Le Pen would go ahead on 17 or 24 January.

The National Front, with its hard-line and anti-immigrant policies, made strong gains in regional elections earlier this year and has maintained about 15% support nationwide.