The scene is set for a long legal battle

Some 2,500 gay couples have wed since the city's mayor defied state law, granting marriage licences.

Opponents want the mayor's actions - and the resulting marriages - annulled.

Several US states are debating new laws after the Massachusetts Supreme Court ruled that gay marriage is a constitutional right in their state.

San Francisco Mayor Gavin Newsom hailed the twin rulings by the Superior Court - which hears serious civil and criminal claims - as a victory for the city.

But conservative groups are determined to take their case to higher courts.

'Long legal battle'

Mayor Newsom took the decision last Thursday to lift a state ban on same-sex unions on the grounds that the ban was a form of discrimination.

The weddings went ahead after San Francisco Superior Court Judge James Warren denied injunctions sought by conservative groups to block same-sex unions.

These are just the early stages of what's going to be a long legal battle Erwin Chemerinsky University of Southern California

The groups were told to refile their lawsuits on Tuesday, as the judge said they did not give a required 24-hour notice to the San Francisco attorney's office.

In the first case brought by the Campaign for California Families (CCF), Superior Court Judge Ronald Quidachay postponed a decision until Friday. He asked the group to inform the city or court of its lawsuit details before he would hear it.

In the second ruling, Judge Warren refused to grant the conservative Alliance Defense Fund (ADF) a temporary restraining order barring the city from carrying out further same-sex marriages.

But he agreed to order the city to stop issuing the licences or return to court on 29 March and explain why not.

Erwin Chemerinsky, a University of Southern California legal scholar, described Judge Warren's ruling as a short-term victory for the city.

But the final decision will ultimately rest with a higher court, Professor Chemerinsky said.

"This is an issue that is going to be decided by the California Supreme Court," AP news agency quoted him as saying.