The UN's special envoy on fighting Aids in Africa has accused the United States of endangering the gains Uganda has made in containing the disease.
Lewis said the Ugandan government was undermining condom use
Stephen Lewis told the BBC that Uganda - under pressure from Washington - was putting greater emphasis on abstinence to tackle the disease than condoms.
His remarks follow a report by US health campaigners saying the country was facing a condom shortage.
Ugandan denies any change in policy and the US has rejected the UN accusation.
Mr Lewis said: "Over the last eight to 10 months, there's been a very significant decline in the use of condoms, significantly orchestrated by the policies of government."
"At the moment, the government of Uganda appears to be under the influence of the American policy through the presidential initiative of emphasising abstinence far and away over condoms," he said.
He suggested US President George Bush, who launched his multi-billion dollar campaign to tackle Aids in Africa two years ago, was acting under the influence of the religious right in US.
A senior US official rejected Mr Lewis's criticism, saying the current administration supported condom use as part of a balanced programme that included prevention.
"The statements that I have heard are completely untrue and completely mischaracterise effective prevention programmes," Mark Dybul, deputy US global Aids co-ordinator told Reuters news agency.
The UN envoy said condoms were now in short supply in Uganda and had tripled in price.
He said political leaders in Uganda were demeaning the value of condoms in favour of abstinence.
US-based Center for Health and Gender Equity reported that Uganda has been facing a condom shortage for 10 months.
But Ugandan Health Minister Mike Mikula rubbished the report, saying condoms remained a vital part of the country's Abstinence, Be faithful and Condoms (ABC) strategy.
"The weight of the ABC is all equal in that abstinence has been one of the critical strengths of Uganda's ability to reduce the prevalence in the country.
"And obviously, being faithful, which is the B has equally done very well. But condoms and the distribution of condoms continues unabated."
He said 65 million condoms had been procured about two months ago and another 80 million were on the way.
Uganda is often held up as a model of how to fight HIV/Aids, with infection rates falling from 15 to 5%.