The capital of Mexico has broken away from the tradition of the conservative Roman Catholic country by approving gay civil unions on Thursday.

|PIC1|Supporters and protestors rallied outside Mexico City's assembly as it passed legislation that legally recognises gay civil unions in the capital, the first such vote by a legislative body in the history of Mexico, reports The Houston Chronicle.

The bill, which does not approve gay marriage but rather allows same-sex couples to register their union with civil authorities, enjoys the support of Mexico City's Mayor Alejandro Encinas who is expected to later sign it into law.

Although Mexico remains a deeply Roman Catholic country, its capital has been governed since 1997 by the left-leaning Democratic Revolutionary Party, or PRD, which has had a stormy relationship with the Catholic Church over a number of issues including abortion.

The legislation was passed with a vote of 43 to17 making Mexico City only the second Latin American city to authorise gay unions after Buenos Aires took the controversial step in 2002.

Meanwhile, lawmakers in the state of Coahuila, which borders with Texas in the US, have proposed the introduction of a similar law.

Prominent gay activist Alejandro Brito said: "This is a triumph for the gay movement in Mexico like we've never seen before. We hope this will reinvigorate the movement and inspire us to fight for our full rights.

"We think there will be a chain reaction. We have to keep fighting to push it through in other states," he said.

Conservative groups, however, are determined to prevent the spread of such legislation to other states.

Guillermo Bustamante, president of the National Parents' Union, which represents hundreds of parents' associations nationwide, called the Mexico City bill a "tyranny of the minorities", as he argued that homosexuals represent "not even one in 100 Mexicans".

"To legalise the union between people of the same sex is to legalise an aberrant act. It's anti-natural," he said.

The Catholic Church has also been a longstanding opponent of pro-homosexuality legislation.

Hugo Valdemar, spokesman for the archdiocese of Mexico City, said that radical groups like the PRD were "very angry with the Catholic Church".

"This is clearly revenge. But the Mexican people are not ready for gay marriage," he added.

The Mexican Council of Bishops warned that the law is the first step toward legalising gay marriage and adoption by gays, a prospect not ruled out by one of the bill's two sponsors, legislator Enrique Perez Correa, who said it could be a stepping stone to full recognition of same-sex marriage and other measures.

Paula Adriana Soto, a lawmaker with the conservative National Action Party - the party of President Vincente Fox and President-elect Felipe Calderon - said that the law simply "conceals a marriage between people of the same sex," which is prohibited by Mexico City civil law.

Jorge Serrano, of the National Pro-Life Committee, said his group would consider seeking a court injunction in the next few days to prevent the legislation from going into effect.