Colombia has become the fourth Latin American country to legalise same-sex marriage, in a move described by one activist as "a victory against the Church."

The country's highest court, the Constitutional Court, has ruled for the first time homosexual couples can marry in the same way heterosexual couples do.

Same-sex couples had previously been free to form civil unions but Colombia, considered a conservative Roman Catholic nation, is now joining Argentina, Brazil and Uruguay in permitting gay and lesbian couples to wed.

The decision, which was backed by President Juan Manuel Santos' government, was widely predicted after a 6-3 decision earlier this month to reject one justice's opinion that officials should be stopped from registering same-sex unions as marriages.

Quoted in the English-language newspaper, Colombia Reports, Luis Rodriguez, a gay rights activist in Santiago de Cali, said: "This is a victory against all the conservative political parties, against the Catholic church and everyone who tried to block our rights."

Earlier this year, Pope Francis, the first ever pontiff from Latin America, reaffirmed the traditional Catholic understanding of marriage as a union between one man and one woman.