North Carolina voters approved an amendment to the state constitution prohibiting same-sex marriage.

Sixty percent of those who turned out to vote in the referendum on controversial Amendment One approved it, making North Carolina the 31st state to approve a measure of this kind.

North Carolina's legislature passed a law in 1996 to bar gay marriage in the Tarheel State.

Since early Tuesday morning there were people at the polling places despite the rain and bad weather in some parts of the state, a level of participation not seen in decades.

Groups in favor and against the measure spent more than $3.5 million in a contest that captured national attention.

"It's a mistake that North Carolina residents have made, but it's the start of a legal battle to remove this type of discrimination from our state constitution," Daniel Valdez of the Charlotte Lesbian and Gay Fund told Efe.

Groups supporting the amendment argued that approving it is a moral matter that seeks to preserve the family.

The approval of the amendment is a victory for the most conservative sectors at a time when pressure on President Barack Obama is rising to declare whether or not he supports same-sex marriage.

Vice President Joe Biden recently said he feels "comfortable" with same-sex couples getting married and Education Secretary Arne Duncan offered explicit support for the idea.

As a Democratic presidential candidate in 2008, Obama gave his support to civil unions between people of the same sex, but he expressed his opposition to gay marriage.

Nevertheless, in late 2010 Obama commented that his stance on the issue was "evolving," although to date he has always avoided giving his explicit support to marriage between homosexuals.

Gay marriage is legal in the states of New York, Connecticut, Iowa, Massachusetts, New Hampshire and Vermont, as well as in the District of Columbia.

In addition, in Washington state same-sex couples will be able to marry as of June 7 and in Maryland gay marriage will be legal starting in 2013.

Delaware, Hawaii, Illinois, New Jersey and Rhode Island allow civil unions between homosexuals.

Half of Americans support the legal recognition of homosexual marriages, according to a survey released Tuesday by Gallup.