Mexico City’s assembly on Thursday voted for the first time in the country’s history to legally recognize gay civil unions, a measure that will provide same-sex couples with benefits similar to those of married couples. The mayor was expected to sign the measure into law.

The bill, which does not approve gay marriage, allows same-sex couples to register their union with civil authorities, granting them inheritance and pension rights, as well as other social benefits. Lawmakers were still finalizing the details.

Heterosexual couples who are not legally married can also be registered under the legislation.

The bill was severely criticized by the Catholic Church and conservative civil groups. It passed by a vote of 43-17, with all the opposition coming from the National Action Party of President Vicente Fox and president-elect Felipe Calderon.

The party is known for its opposition to abortion and its support for traditional families.

Mexico City is a federal district with its own legislature, and the law will apply only to residents of the capital, with a population of 8.7 million. This is the first time any state legislature has approved such a law anywhere in Mexico.