REF: Tens of thousands of people have rallied in Paris against a new French law allowing same-sex marriage.
Police estimate that up to 150,000 people joined marches that converged on the city centre, but organisers put the figure close to one million.
Clashes erupted after the rally finished between far-right activists and riot police. The authorities said nearly 100 people were arrested.
On Saturday 50 people were detained for blocking the Champs-Elysees.
The same-sex marriage bill, which also legalises gay adoption, was signed into law by President Francois Hollande last week, after months of heated debate.
I am an ass. I voted Hollande”
Anti-gay protester in Paris
French people have been bitterly divided over the issue. On Tuesday, a far-right historian shot himself dead in Notre Dame cathedral, leaving messages in which he denounced gay marriage.
During Sunday’s protests, demonstrators headed in columns from a number of points in Paris to the Invalides complex.
Some marchers drove donkeys, one of which bore a placard which read: “I am an ass. I voted Hollande”.
The leader of the UMP conservative opposition party, Jean-Francois Cope, headed one of the processions.
Despite some 4,500 police deployed in Paris, clashes broke out at the end of the day between far-right activists and police, filling the Invalides complex with tear gas.
The interior ministry said 96 people were arrested.
Leading activist Virginie Tellen – better known as Frigide Barjot – earlier in the day greeted protesters arriving to Paris from across France at a Paris train station.
But she did not take part in the march, citing threats from far-right groups.
One UMP member of parliament, Jacques Myard, told BBC News that the law had been passed by the governing party “by force” and his party would review it if re-elected.
Mr Myard told the BBC there was a “huge gap between this government and the citizens” over the marriage issue.
“This is something we cannot accept because of the fate of the children,” he said.
“Those people are playing God, because they want to marry, but it won’t stop at this stage. Then they will adopt, and then we will have children in families where there is no father or no mother.”
The leader of France’s far-right National Front, Marine Le Pen, was also among the marchers.
On Saturday evening, a group of protesters chained themselves to metal barriers they had placed in the middle of the Champs-Elysees.
Some released smoke bombs before police moved in and arrested them. Nobody was hurt.
Opposition to gay marriage has become conflated with all sorts of other anti-government grievances coming from the right and the atmosphere in the country is particularly volatile, the BBC’s Hugh Schofield says.
France is now the ninth country in Europe, and 14th globally, to legalise gay marriage.