PARIS (AFP) -- French Prime Minister Dominique de Villepin said that he would not take part in a party primary that is set to endorse his center-right colleague and rival Nicolas Sarkozy as candidate in April's presidential elections.

Villepin said it would be inappropriate for him to vote in the primary organized by the ruling Union for a Popular Movement (UMP), in which Sarkozy is running unchallenged.

"Since the president of the republic has not announced his intentions, as head of government I am not in a position to participate in this vote," Villepin told Canal Plus television.

Although at 74 Chirac is thought highly unlikely to seek a third term, the president sowed confusion this week with a series of speeches that commentators saw as laying the groundwork for a rival bid to Sarkozy.

According to an Ifop poll published on Sunday, 81 percent of French voters think Chirac should not run again, and 70 percent believe he should not even play a role in the election campaign.

Though a string of polls have put them neck-and-neck, the latest figures show Sarkozy slipping behind his Socialist rival Segolene Royal, who is riding a wave of enthusiastic support for her bid to become France's first woman president.

An Ifop poll published on Sunday had Royal winning with 50.5 percent of the vote in the second round on May 6, with 49.5 percent for Sarkozy.

Last week a separate survey by CSA suggested a four point advantage Royal, who was predicted to pick up 52 percent against Sarkozy's 48 percent.