US defence secretary Robert Gates says he doubts that the ban on out gay troops will be lifted before the end of the year.

He said he thought it was unlikely that the Senate would vote on the matter this month.

If a vote is delayed until 2011, the repeal measure is less likely to pass as the Republicans will have gained control of the House and become stronger in the Senate.

Mr Gates, speaking to journalists while on a visit to Afghanistan, said: “I’d have to say I’m not particularly optimistic that they’re going to get this done.

“I would hope that they would,” he added.

The defence secretary repeated his concern that repeal would come through the courts rather than the Senate, which he said could mean the law being lifted too quickly to implement training to ensure that the change is smooth.

A measure to repeal the policy is attached to the Defence Authorisation Bill. It passed the House in the summer but a vote in the Senate was blocked in October by Republicans.

It is not clear whether the Senate has enough votes or time to pass the measure.

A Pentagon report released last week said that the ban on out gay troops in the US military can be lifted safely without too much disruption.

The report said that the ban could even be lifted now, in wartime, without harming troops or the military’s ability to do its job.

Most troops – around 70 per cent – surveyed for the report said they would not mind serving alongside out gay colleagues.

However, around 30 per cent of servicemembers in front-line combat roles strongly objected to serving alongside openly gay colleagues.