Five gay and lesbian couples in the US state of Alaska filed a lawsuit on Monday challenging the state’s ban on same-sex marriage.

Included as plaintiffs in the lawsuit are four same-sex couples married outside of Alaska and one unmarried couple.

The challenge states that the state’s ban on same-sex marriage is unconstitutional, stating that it violates their rights to due processes and equal protection.

It seeks to have enforcement of the same-sex marriage ban stopped, and therefore to allow gay couples to wed, as well as to have the state recognise out-of-state marriages.

The couples in a statement said they had filed the lawsuit “because marriage should be available to all loving couples.”

A 1998 voter-approved same-sex marriage ban defines marriage as specifically between one man and one woman.

The Supreme Court in the US state of Alaska last month ruled that same-sex couples deserve equal access to a tax benefit as straight couples.

The case was initiated by the American Civil Liberties Union (ACLU) in 2009, and sought to allow same-sex couples access to a property tax exemption.