Argentina on Thursday became the first country in Latin America to legalize same-sex marriage, following a landmark Senate vote which stirred controversy in the majority Roman Catholic nation.

The law was backed by the center-left government of President Cristina Kirchner and adopted in a 33-27 vote, with three abstentions, after 15 hours of debate.

"It's a positive step which defends the right of the minority in Argentina," Kirchner said to Argentine media on Thursday during a visit to China.

The issue raised heated debate in this nation of 40 million, 90 percent of whom describe themselves as Roman Catholic.

The influential Catholic Church lashed out at the decision, after having called unsuccessfully for a national referendum on the issue which drew support from members of opposing political parties.