Former prime minister Dominique de Villepin has admitted he will need "a miracle" to gain the support needed to run as a candidate in France's presidential election.

De Villepin said that he had failed to obtain the necessary 500 signatures of French mayors needed to stand.

The veteran politician, and fierce rival of Nicolas Sarkozy, who is seeking a second term in office in the two-round election in April and May, told French 2 television that he needed another 30 signatures before tomorrow's deadline and doubted he would get them.

"But the republican miracle exists and I'm hoping for it," he said.

De Villepin's independent centre right party "United Republic" said his situation was a "paradox of the republic".

"It's without doubt easier for a fantasy or extreme candidate to get the 500 signatures as it's less risky for some mayors than giving their support to a former prime minister."

The former PM, 58, who was running on an anti-Sarkozy ticket, said he would not be rallying his supporters behind another candidate saying this was "not part of my temperament or my programme".

De Villepin, a poetry-writing career diplomat who also served as a French foreign minister, is most famous outside of France for his impassioned speech to the United Nations Security Council in 2003 opposing the invasion of Iraq. He vowed to continue in politics. "And I will give it all my strength and energy as I have for the last 35 years," he said.

Opinion polls credited de Villepin with less than 1 per cent of the vote in the first round of the election in April, but he remained a risk to Sarkozy who has the far right candidate Marine Le Pen, of the Front National, snapping at his heels and who needs all the support he can get.

Candidates who want to stand in the election must present their 500 supporting signatures by Friday.

Sarkozy's closes rival, the frontrunner socialist François Hollande and Le Pen have the necessary signatures. At least four other candidates are expected to be able to stand.