Same-sex couples in the US state of Utah began queuing to marry after a judge ruled that the state’s equal marriage ban was unconstitutional.

A county clerk in the city of Salt Lake City began issuing marriage licences just hours after Judge Robert Shelby made the ruling.

In his ruling, he noted the 2004 voter-approved ban on equal marriage, and said that it violated same-sex couples’ right to equal protection.

Three couples brought the case after being denied marriage licences, or legal recognition by the state.

Judge Shelby said that the state had not proven that allowing same-sex couples to marry would affect straight couples’ unions.

“In the absence of such evidence, the state’s unsupported fears and speculations are insufficient to justify the state’s refusal to dignify the family relationships of its gay and lesbian citizens,” he wrote.

Couples began marrying around an hour after the ruling, and the first were Michael Ferguson and Seth Anderson, who were also joined by State Senator Jim Dabakis, and his longtime partner Stephen Justesen, according to BBC reports.

State officials have said they will appeal the decision and are to seek an order to prevent more marriage licences from being issued to same-sex couples.

The Attorney General’s office in the state said it had requested an emergency stay to stop the issuing of marriage licences to same-sex couples, “pending the filing of an appeal”.

Governor Gary Herbert expressed that he was “very disappointed an activist federal judge is attempting to override the will of the people of Utah”.

“I am working with my legal counsel and the acting attorney general to determine the best course to defend traditional marriage within the borders of Utah.”

The constitutional ban received 66% of the vote back in 2004.

On Thursday, the New Mexico State Supreme Court issued a ruling to legalise equal marriage. Eight of the state’s 33 counties started issuing marriage licences to same-sex couples in August, when a county clerk in southern New Mexico independently decided to allow the ceremonies.