France's conservatives are left without a new boss on Monday after results of a tough election race remained unclear while both contenders claimed victory and allege fraud.

Jean-Francois Cope, general secretary of the right wing party Union for a Popular Movement (UMP) party, said in the early hours of Monday that he was 1,000 votes ahead of former prime minister Francois Fillon, who also declared that he won the party's leadership 20 minutes later.

The race to lead France's conservative opposition descended into chaos with both contenders alleging fraud in the voting on Sunday, prompting a pause in ballot-counting which was resumed on Monday at 10 a.m. (0900 GMT).

The vote was intended to pick a successor to former president Nicolas Sarkozy. The victor will lead the center-right party into local elections in 2014 and will be in a strong position to win the party's nomination for president in 2017.