WASHINGTON (AFP) - US Attorney General Eric Holder will expand government recognition of same-sex marriages in all federal courtrooms and prisons on Monday, Feb 10, 2014, and ensure they receive the same benefits as heterosexual ones.

The inaugural move, which Mr Holder plans to announce later on Saturday at a gay rights dinner gala in New York, marks a major gain for advocates of same-sex couples after the Supreme Court issued two rulings expanding gay marriage rights last year.

Under the new policy, same-sex couples will enjoy the privileges even in states that do not recognise their marriages, so long as they legally married in another state.

Among the key benefits the Justice Department will now ensure are extended to same-sex couples are the compensation fund for the September 11, 2001 attacks, as well as death and educational benefits for the surviving spouses of police officers and firefighters injured or killed in the line of duty.

"In every courthouse, in every proceeding, and in every place where a member of the Department of Justice stands on behalf of the United States, they will strive to ensure that same-sex marriages receive the same privileges, protections and rights as opposite-sex marriages under federal law," Mr Holder said in advance excerpts of his speech.

Same-sex couples would also be held to the same legal standard as their heterosexual counterparts on matters such as how debts are handled in federal bankruptcy proceedings and visitation policies at federal prisons, as well as compassionate release or sentence reductions in certain cases.

Mr Holder plans to detail the new policy in a memorandum to employees on Monday.

The text will "formally instruct all Department employees to give lawful same-sex marriages full and equal recognition, to the greatest extent possible under the law", according to the excerpts.