France has become the ninth country in Europe and the 14th country worldwide to legalize gay marriage.
The country's president, Francois Hollande, signed the controversial bill Friday after the Constitutional Council rejected a challenge by the right-wing opposition, the BBC reported.
"I have taken [the decision]; now it is time to respect the law of the Republic," Hollande said.
France's official journal announced Saturday the bill had been passed into law following the Constitutional Council approving it late Friday, Reuters reported.
But while gay rights groups celebrated the decision, opponents of the measures vowed to fight it, the Telegraph reported.
Lobby groups have called a major protest rally scheduled for May 26 in Paris, and similar to previous protests it is expected to draw hundreds of thousands of people, AFP reported.
Frigide Barjot, the leader of opposition to gay marriage and a political activist, told Reuters the protest would draw millions into the streets.
Hollande made "marriage for all" a main focus of his presidential election campaign last year.
"I will ensure that the law applies across the whole territory, in full, and I will not accept any disruption of these marriages," said the president.
French Justice Minister Christiane Taubira said the first gay marriages could be held as early as next month.
The issue of gay marriage has been extremely controversial and divided France, which is officially secular but overwhelmingly Catholic. Violent street protests against the bill are expected to continue, AFP reported.
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