Image copyright AP Image caption April DeBoer, left, and Jayne Rowse, right, at home with their adopted children in Michigan

A US federal judge has struck down a ban on gay marriage in the state of Michigan.

Two Detroit-area nurses successfully argued that the ban violated their rights under the US constitution.

One local official said she would start issuing marriage licences to same-sex couples from Monday, but the state is planning to lodge an appeal.

Seventeen states and the District of Columbia currently issue licences for same-sex marriage.

'Equal protection'

The case was brought two years ago by partners Jayne Rowse, 49, and April DeBoer, 42, who want to get married.

Media playback is unsupported on your device Media caption A retirement project for elderly members of the gay community in Minneapolis

"Many Michigan residents have religious convictions whose principles govern the conduct of their daily lives and inform their own viewpoints about marriage," US District Judge Bernard Friedman wrote in Friday's decision.

"Nonetheless, these views cannot strip other citizens of the guarantees of equal protection under the law."

Michigan Attorney General Bill Schuette promptly moved for an appeal to uphold the state's ban on gay marriage, which was approved by voters in 2004.

Bans on gay marriage have been quashed in recent months in Texas, Utah, Oklahoma and Virginia, though appeals have put those cases on hold.