A Washington judge has ruled that the names of those who signed a petition against equal rights for gay couples can be kept secret.

Gay marriage opponents said publishing the details could lead to threats and harassment, although gay groups argue that changing the law should be an open process.

Yesterday, US District Judge Benjamin Settle in Tacoma granted a preliminary injunction barring the publication of the names.

Earlier this year, the state passed an “everything but marriage” law, allowing gay couples in domestic partnerships access to all rights enjoyed by straight married couples.

Religious and conservative groups have now managed to collect enough signatures in opposition to allow voters to approve or reject the move in a November referendum, known as R-71.

Gay marriage advocates have attempted to block the referendum by arguing that secretary of state Sam Reed accepted petitions which were not gathered correctly.

Part of the effort against the referendum are plans to publish the names of those who signed for it online. Two gay rights groups, WhoSigned.Org and KnowThyNeighbor.org, have already done this in a number of states.

Sponsors of R-71 are fighting to keep the petitions secret. Although they are recognised as public documents and may be viewed by anyone, opponents believe that those who do not support equal gay rights may be targeted with harassment.

Reed’s spokesman argued that the judge’s decision was “a step away from open government”. The state attorney general’s office is reportedly considering whether to appeal the injunction.

The group leading the campaign against expanded gay rights, Protect Marriage, claimed supporters had told them they were too scared to sign the petition for fear of attack.

Washington Families Standing Together has now said it will focus on persuading voters to retain the rights for gay couples, rather than pursuing the issue through courts on a technicality.

The law was due to take effect in July but has been put on hold until the November 3rd ballot, where voters will be asked to approve or reject it.