Iowa's Supreme Court has ruled that a ban on same-sex marriages in the US state was unconstitutional.

The judges rejected an appeal against a lower court's 2007 ruling that the ban violated the rights of gay men and women in the state.

The case stems from a 2005 suit filed by a New York-based gay-rights group on behalf of six gay and lesbian couples.

Iowa now becomes the third US state to allow same-sex marriages after Connecticut and Massachusetts.

In 2007, Polk County Judge Robert Hanson ruled that the state's 1998 Defense of Marriage Act, which defines marriage as solely between a man and a woman, violated the couples' constitutional rights.