This week's vote follows a ruling by the Vermont Supreme Court last December that gay couples were being unfairly denied the rights of marriage.

The move will ensure legal parity

Under the bill, same-sex partners will be allowed to apply for a licence similar to a marriage certificate, giving them the same benefits as married couples on matters such as life insurance, health care and child custody.

Couples wishing to separate would have to go to court.

Move welcomed

Thomas Little, chairman of the House Judiciary Committee, said: "The continued denial of these legal protections, benefits and responsibilities to a small but vulnerable class of Vermont's citizens diminishes their humanity, dignity, freedom and independence."

Gay rights activists have welcomed the legislation, saying it sets an example to the rest of the United States.

Opponents complain that the law goes too far.

Californian voters backed a pre-emptive move last month to ban official recognition of gay marriages.