BOSTON (AP) - In a disappointment for the gay rights movement, the state's highest court ruled Thursday that same-sex couples from states where gay marriage is prohibited cannot tie the knot in Massachusetts.

Gov. Mitt Romney, a Republican who is a considering a run for president in 2008, welcomed the decision, saying he did not want Massachusetts to become "the Las Vegas of same-sex marriage."

The Supreme Judicial Court upheld a 1913 state law that forbids nonresidents to marry in Massachusetts if their marriage would not be recognized in their home state.

If the court had struck down the law, Massachusetts would have been thrown open to gay couples from across the country to get married. Then they could have returned to their home states to fight for legal recognition for those marriages.

Massachusetts "has a significant interest in not meddling in matters in which another state, the one where a couple actually resides, has a paramount interest," Justice Francis Spina wrote.

The state "can reasonably believe that nonresident same-sex couples primarily are coming to this commonwealth to marry because they want to evade the marriage laws of their home states, and that Massachusetts should not be encouraging such evasion."

The ruling leaves in legal limbo an undetermined number of out-of-state gay couples who got married in 2004 in Massachusetts when it became the first state to let gays wed.

Arline Isaacson of the Massachusetts Gay and Lesbian Political Caucus called the decision "a painful reminder that we remain second-class citizens."

"It's painful to know you'll be treated equally under the law if and only if you happen to live here," she said. "Otherwise, you are completely unequal as a gay person."

But the governor said: "It's important that other states have the right to make their own determination of marriage and not follow the wrong course that our Supreme Judicial Court put us on."

More than 6,000 gay couples have married in Massachusetts since the same court ruled in a landmark decision in 2003 that the state Constitution gives same-sex couples the same right to marry as heterosexual ones.

Eight gay couples from surrounding states had challenged the 93-year-old law. Five of those eight couples received marriage licenses in Massachusetts before the governor ordered city and town clerks to enforce the 1913 law.

In Thursday's ruling, six justices ruled against the gay couples in two separate opinions. Only one member of the seven-justice court dissented.

However, the court sent the cases involving couples from Rhode Island and New York back to a lower court, saying it was unclear whether those states prohibit same-sex marriage.

New York's top officials have said same-sex marriage is illegal in the state, although that interpretation is being challenged.