Scores of lesbian and gay couples have registered for marriage licences in Mexico City, the first place in Latin America to legalise gay marriage with the first ceremonies taking place in ten days.

The city passed a law in December of last year that gives gay and lesbian couples the same rights to marry, adopt children, secure loans, benefit from their partner’s insurance policies and inherit without paying tax.

Although the law only applies to residents of Mexico City, they are recognised in the rest of the country’s 31 states. Intriguingly the actual requirements to prove residency are low: a utiliy bill, even in someone else’s name.

However, the law is being challenged in the country’s Supreme Court by the Mexican federal government, arguing it breaches the country’s constitutions.

A statement from the federal Attorney General’s Office said the law “violates the principle of legality, because it strays from the constitutional principle of protecting the family”.

But David Razu, the Mexico City legislator who first proposed the law told the AFP news agency that he is confident the courts will uphold the new law: “There is always a wave of reaction to these kinds of measures, but we are prepared to face it.”

The Roman Catholic archbishop of Mexico, Cardinal Noberto Rivera Carrera, deemed the bill “immoral” and “reprehensible” last month.

City officials have said action from the Attorney General’s Office would not prevent the law coming into force.

According to On Top Magazine, city legal advisor Leticia Bonifaz told the Excelsior newspaper that she was “totally confident that this is an issue of fundamental rights”.

In December, two gay men from Argentina had Latin America’s first gay marriage.

Jose Maria Di Bello and Alex Freyre married in Ushuaia, the capital of Argentina’s Tierra del Fuego state where sympathetic state officials backed their bid.