UK aid threat to anti-gay nations
Britain has threatened countries which ban homosexuality with losing aid payments unless they reform, David Cameron said.
But he conceded that "deep prejudices" against gays in some countries meant the problem would persist for years.
The Prime Minister said he had raised the issue with leaders of some of the states involved when he attended the Commonwealth Heads of Government Meeting (CHOGM) in Australia over the last two days.
Britain was "putting the pressure on" he said over an issue that was one of the stumbling blocks of a summit beset by failure to make significant progress on strengthening human rights protections.
It was not a problem that would be solved however by the next time Commonwealth leaders are due to meet in Sri Lanka in 2013. Mr Cameron also issued a clear warning to Sri Lanka to improve its human rights record or face boycotts of the 2013 summit.
He declined to discuss whether the UK could stay away but said he shared a "similar view" of the need to change with Canada, whose prime minister Stephen Harper has said he will not attend.
Ending bans on homosexuality was one of the recommendations of an highly-critical internal report into the future relevance of the Commonwealth - authored by experts from across the member nations including ex-Foreign Secretary Malcolm Rifkind.
"We are not just talking about it. We are also saying that British aid should have more strings attached," Mr Cameron told BBC One's Andrew Marr Show in an interview recorded at the summit in Perth.
"This is an issue where we are pushing for movement, we are prepared to put some money behind what we believe. But I'm afraid that you can't expect countries to change overnight.
"Britain is one of the premier aid givers in the world. We want to see countries that receive our aid adhering to proper human rights. We are saying that is one of the things that determines our aid policy, and there have been particularly bad examples where we have taken action."