France’s lower house of Parliament backed same-sex marriage in a vote yesterday, paving the way for it to enter law after street marches rallied hundreds of thousands of demonstrators both for and against it.

The move is France’s most important social reform since the abolition of the death penalty in 1981 but is opposed by social conservatives in the majority Catholic country, together with many French Muslims and evangelical Christians.

Assuming it is passed by the Senate upper house in an April 2 vote, France will join 11 other countries including Belgium, Portugal, the Netherlands, Spain, Sweden, Norway and South Africa where same-sex marriage is legal.

A further nine US states and Washington DC allow same-sex marriage while British MPs earlier this month backed it in an initial vote.

“We’ve waged a great and noble battle,” Justice Minister Christiane Taubira, the Bill’s main promoter, told journalists ahead of the 329 vs 229 vote in favour of the Bill.

President Francois Hollande’s Socialists hold a majority in the National Assembly, which allowed them to overcome attempts by opponents to delay proceedings with around 5,000 amendments that took over 100 hours of acrimonious debate. The Socialists and their allies together hold a majority in the Senate.

Known in France as “marriage for all”, the gay marriage Bill has proven to be the most divisive social initiative undertaken by Hollande’s government in his nine months in power.

On January 13, a survey by pollster CSA showed it had split the population roughly in two, with a slim majority of 51 per cent in favour and 43 per cent opposed.

Legislators dropped a plan to also allow lesbians access to artificial insemination that proved highly contentious among voters. A separate Bill covering that is due for debate later this year.

Some two thirds of the French describe their religion as Roman Catholic, though church attendance has dwindled since the 1970s.