A city in Arizona has become the first in the state to allow same-sex partners to have civil unions, despite threats of legal action made by the state’s attorney general.

The council of Bisbee, a former mining town now populated by a large number of artists and retirees, voted 5-2 on Tuesday to pass legislation allowing civil unions between couples of any gender.

Gene Connors, a council member in his first term, proposed the measure. He said after the vote: “We’re just acknowledging the people that live here. It’s a big step in the right direction for a tiny town … it’s pretty neat.”

Arizona’s attorney general, Tom Horne, wrote to the council before they voted, telling them they had “no authority” to legalise same-sex unions.

“The only proper way to change a statute is through the legislature, not through actions of the city council attempting to change a state statute within its boundaries,” said Mr Horne. He has threatened to block the measure in court before it comes into effect, but has yet to follow up on that promise.

Bisbee resident James Cool voiced his support for the measure: “The train in this country has left the station on civil unions, just as it did on interracial marriage and voting rights. If you don’t like civil unions, don’t get one.”

Some opponents argued that the legislation could result in falling levels of tourism to Bisbee, while others said same-sex unions were an “abomination”.

If no legal challenge is submitted civil unions should be able to take place in Bisbee from May this year, but they would only be recognised within city limits.

An Arizona state Representative, Matt Salmon, said this week that he remained opposed to gay marriage despite having an openly gay son. 

Last month the US Supreme Court heard two major cases related to equal marriage, one challenging a California ban and the other challenging a federal law restricting tax and other marriage benefits to opposite-sex couples only. The court is expected to issue rulings in June.