Mayor Marcelo Ebrard was a guest of honour at the weddings of Judith Vazquez and Lol Kin Castaneda and the other couples who tied the knot in a city building, despite harsh criticism from the Roman Catholic Church and a campaign against the measure by President Felipe Calderon's conservative National Action Party.

Ms Vazquez, a 45-year-old small-business owner, and Ms Castaneda, a 33-year-old psychologist, signed and put their thumb print on the official documents.

Then they sealed their union with a kiss amid cheers from family and friends gathered in the colonial-era building's courtyard, decorated with calla lilies, banners with the colours of Mexico's flag and a sign that read Tolerance, Liberty, Equality, Solidarity.

"This is the mark of freedom," said Ms Vazquez, raising her thumb.

Ms Vazquez said she and Ms Castaneda considered themselves married ever since they moved in together six years ago.

"The difference now is that the state will recognise it," she said while getting her hair done at home before the wedding. "This is a victory for all. For us this is a day of celebration."

Mexico City's legislature passed the first law explicitly giving gay marriages the same status as heterosexual ones in December.

The legislation also allows same-sex couples to adopt children.

For now the law applies only to residents of Mexico City, though a marriage performed in one state must be recognised in the rest of the country.