French ex-president Nicolas Sarkozy saw his ambition to lead the country for a second time dashed as he suffered a crushing defeat to his former prime minister, François Fillon, in the first round of a centre-right primary on Sunday.

Fillon will now face off against another former prime minister, Alain Juppé, in a November 27 run-off to become the centre-right Les Republicains' nomination in May's presidential election.

With ballots counted at 8,709 polling stations out of a total 10,229, Fillon was seen gathering 44.1 percent of the votes, Juppé 28.2 percent and Sarkozy 21.0 percent.

Sarkozy, president from 2007-12, said he would now back Fillon, a surprise frontrunner in what is the centre-right's first ever presidential primary, in the run-off vote.

As results trickled in Sunday evening and the gap between Sarkozy and Juppé became ever wider, Sarkozy had little choice but to concede defeat.

"I failed to convince a majority of voters," Sarkozy told supporters and reporters at his campaign headquarters.

I hold Alain Juppé in high esteem, but I feel closer to Francois Fillon's political choices," he said, indicating he would vote for his former prime minister.

"I wish the best for France and for the person who will lead the country that I love," Sarkozy added later on Twitter.

(France24)