The Obama administration called state bans on same-sex marriage "incompatible with the constitution", as a brief was filed in the US Supreme Court in support of couples challenging such bans in Kentucky, Michigan, Ohio and Tennessee, a media report said on Saturday.
"The marriage bans challenged in these cases impermissibly exclude lesbian and gay couples from the rights, responsibilities and status of civil marriage," CNN cited Solicitor General Donald B. Verrilli Jr. as saying.
He said the states have "burdened petitioners in every aspect of life that marriage touches, from the mundane to the profound".
The brief marks the first time the administration has formally made a filing with the court supporting its position that bans on gay marriage should be declared unconstitutional nationwide.
The court will hear arguments in the state cases on April 28.