Same-sex couples in New York are one step closer to being able to marry after a judge ruled Friday that a ban on gay marriage violates the state's constitution.

State Supreme Court Justice Doris Ling-Cohan was ruling on a lawsuit brought by five homosexual couples.

She said the clerk of New York City could not refuse to grant marriage licences simply because the two people seeking them are the same gender.

The state's constitution promises equality of treatment to all New Yorkers.

The city's law department said it is reviewing the decision before deciding whether New York City will start issuing marriage licences to gay couples.

Same-sex marriage hit the headlines in New York early last year, when the mayor of New Paltz, a village outside of New York City, married 25 gay and lesbian couples.

Police laid misdemeanor charges against the mayor, Jason West, then dropped them before reinstating them this week.

He faces a year in jail if found guilty of defying New York's law against uniting two people of the same gender in marriage.

In Wednesday's state of the union address, U.S. President George W. Bush confirmed he still supports amending the American Constitution "to protect the institution of marriage" by banning gay marriage across the country.

This past November, voters in 11 individual states approved state constitutional amendments banning same-sex marriage.