France is set to become the 14th nation in the world to legalise same-sex marriage, after the National Assembly passed it in a final vote after months of debate and heated protests.

The ruling Socialist party and their allies in the lower house of the National Assembly passed the bill 331 in favour – 225 against, giving same-sex couples the legal right to marry and adopt children.

Tensions caused by the bill were so high “legions” of police officers gathered outside the National Assembly with water cannons while the vote took place.

The final remaining step before the bill becomes law is for it to be signed by President Francois Hollande, who gave his formal approval to the bill last November.

Opponents hope he may be pressured into dropping the bill, or that it may be challenged through France’s constitutional council.

However, President Hollande has resolutely stuck by his election promise to legalise same-sex marriage in the face of fierce opposition, which has seen hundreds of thousands of French citizens take to the streets denouncing him and his legislation.

Britain’s Deputy Prime Minister Nick Clegg reacted to the news tweeting: “Marriage should be for all. Excellent that French Parliament approves #equalmarriage law. Let’s make sure UK is next.”

It emerged yesterday that the Speaker of the National Assembly, Claude Bartolone, received a threatening letter containing ammunition powder, asking him to delay the vote.

“Our methods are more radical and direct than the protests, you wanted war, you have it,” the letter stated.

On Friday, the lower house of French National Assembly almost mirrored violent protests outside, as punches were reportedly thrown in a scuffle which lasted several minutes. One minister said he had never experienced such an incident in his 30 years in the lower house.

An estimated 50,000 protesters marched against the bill on Sunday, many of whom were part of the ‘Manif pour Tous’ anti-same-sex marriage group.

A Manif pour Tous demonstration in March drew much larger crowds of around 300,000. A similar march in January rallied an estimated 400,000 people, but earned organisers a €100,000 clean-up bill from the city’s gay mayor.

LGBT rights groups reported a sharp rise in homophobic incidents as opposition to the bill became more widespread.

A young gay cabaret dancer was beaten unconscious at the weekend in Nice, while on 6 April a gay couple were attacked in Paris. One man, left with a fractured skull, said the attack was “the face of homophobia”.

Last week, President Hollande condemned displays of homophobic violence, along with Prime Minister Jean-Marc Ayrault, who also called for calm.