UPDATE 3-Mauritania junta frees president, he vows defiance

(Adds quote from pro-Abdallahi politician, Nouakchott calm)

By Hachem Sidi Salem and Vincent Fertey

NOUAKCHOTT, Dec 21 (Reuters) - Mauritania's military junta on Sunday freed from house arrest ousted President Sidi Mohamed Ould Cheikh Abdallahi, who vowed to fight to return to the office he lost in a bloodless coup in August.

The generals who overthrew Abdallahi, the first democratically elected president of the west Saharan Islamic state, had said this month they would release him as part of negotiations to head off threatened European Union sanctions.

Former colonial power France, which holds the rotating EU presidency, welcomed the release but reiterated the international community's demand that the ousted president be restored to office. "The solution to the current crisis is a return to constitutional order," it said in a statement.

Mauritania's coup leaders have refused to reinstall Abdallahi, who won multi-party elections last year.

The ousted president was freed after he was driven to the dusty coastal capital by security officers from his hometown of Lemden, 200 km (125 miles) to the south. He later returned to Lemden with friends, supporters said.

In an interview published on Sunday by the French newspaper Le Monde, Abdallahi said he considered himself "the legitimate, democratically-elected president".

"I'll push my freedom to the limits the coup leaders put on it. I am firmly resolved to fight to make this coup d'etat fail," he said in the interview, which was conducted shortly before he was freed from house arrest.