A federal judge has upheld a decision to legalise marriage rights for same-sex couples in the American state of Utah.

On Monday, US District Judge Robert Shelby refused to block his own ruling making equal marriage legal in the state.

The case was brought by three couples who had been denied licences or recognition in the state, including one couple who had been legally married in Iowa.

They challenged a ban on equal marriage passed by Utah voters in 2004 by 66%. Judge Shelby said that violated same-sex couples’ rights to equal protection.

Last Friday, same-sex couples in Utah began queuing to marry after Judge Shelby ruled that the state’s equal marriage ban was unconstitutional.

Utah – better known for the Mormon Church than for progressive politics – is the 18th US state to legalise equal marriage.

Judge Shelby turned down an emergency motion from the state asking that his ruling be put on hold.

The state asked the 10th Circuit Court of Appeals in Denver to grant an emergency stay that would have immediately stopped same-sex weddings until the court can rule on whether last week’s decision was valid.

However, Judge Shelby himself heard Monday’s challenge, and rejected it.

Around 900 same-sex couples have since obtained marriage licences from the county clerk’s office in Salt Lake City.

On Monday, Republican Governor Gary Herbert said the judge’s ruling had resulted in “a lot of chaos”.

“This uncertainty is creating a lot of problems for us with the conflicting laws in the state of Utah, what the clerks should be doing, what the tax laws are going to be,” he said in a statement.