A federal judge has ordered that the US state of Ohio must recognise out-of-state same-sex marriages.

Judge Timothy Black’s official ruling came on Monday, but he announced the intention to do so last week.

It orders the state to recognise same-sex marriages performed out-of-state, and criticised the state’s “ongoing arbitrary discrimination on the basis of sexual orientation.”

He said Ohio’s ban on same-sex marriage was unenforceable and against citizens’ constitutional rights

The ruling does not mean the state must perform same-sex marriages.

Attorney General Mike DeWine had already said the state will appeal against the ruling.

Black already in December issued a limited ruling which ordered the state to recognise same-sex marriages for death certificate purposes.

An Ohio US Representative last week called for the impeachment of Black for his intention to strike down the ban.

Judge Black has not issued a stay on the ruling, giving those on both sides of the argument until late on Tuesday to put forward their arguments.