US policy is undermining the efforts of African countries to fight the HIV epidemic, a leading UN figure has said.
Millions of Africans have HIV
Stephen Lewis, UN Special Envoy on Aids, said President George Bush's $15bn Emergency Plan for HIV/Aids was too focused on promoting abstinence.
He said Washington was practising "incipient neo-colonialism" by telling African nations how to fight Aids.
He also accused the West of failing to deliver on funding commitments they had made to fight the disease.
Speaking at the 16th International Aids Conference in Toronto, Mr Lewis said: "No government in the Western world has the right to dictate policy to African governments around the way in which they respond to the pandemic."
Sub-Saharan Africa remains the epicentre of the Aids pandemic, with two-thirds of all people living with HIV coming from the region.
Two million people died of Aids in the region last year and there were 2.7m new infections.
The Bush administration backs an "ABC" plan to fight Aids: Abstinence until marriage; Being faithful to one sexual partner; and if those conditions are not practised, the use of Condoms.
In 2003, the US Government approved a $15bn package over five years to fight the spread of Aids.
But the US Congress has stipulated that a proportion of the funds must be spent on encouraging abstinence-until-marriage programmes.
Mr Lewis said abstinence programmes had been shown not to work.
"That kind of incipient neo-colonialism is unacceptable.
"We're saying to Africa: 'This is how you will respond to the pandemic' and that's not appropriate because African governments are eminently capable of deciding what their priorities are and what the response should be."
"You do not provide money on the condition that they reflect your ideological priorities."
Top US officials have rejected the criticism, denying it promotes abstinence to the detriment of other HIV prevention strategies, or that it is designed to appease conservative Republicans.
Mark Dybul, US Global Aids coordinator, said only 7% of funding for 2005 had been spent on abstinence programmes.
He said: "There is no evidence in support of what they are saying.
"It is colonialistic to not support ABC. ABC was developed by Africans for Africans - we are supporting their strategies."
Speaking to the BBC, Mr Lewis said the West had failed to provide sufficient funds to finance effective long-term prevention and treatment programmes.
"The G8 countries could help to break the back of this pandemic if they viewed it as an emergency like no other emergency - as the worst scourge on the face of the planet since the Black Death of the 14th century.
"That sense of urgency is not yet evident."