Uganda's pioneering Aids programme, which had to an extent shown the world that the epidemic could be turned around in Africa, appears to be in crisis as the government stands accused of obstructing the distribution of millions of condoms while preaching that no sex is the best prevention policy for single people.

Leading Aids activists and the UN special envoy for HIV/Aids in Africa, Stephen Lewis, yesterday urged Uganda to make more condoms available.

They argued that the abstinence-only policies being promoted by the first lady, Janet Museveni, and financed by the US government are not, on their own, going to stop the spread of the disease.

The battle over prevention tactics appears to be coming to a head just days after questions have been asked about the financial management of Uganda's flagship Aids programmes.

Last week the Global Fund for Aids, TB and Malaria pulled all its funding from Uganda's programmes.

After a review by accountants PricewaterhouseCoopers of the handling of Aids funding, the Global Fund suspended five grants worth US$201m (£112m) over two years and demanded that the unit within the Ugandan ministry of health that manages them should be disbanded.

The great successes in Uganda's fight against Aids has been largely credited to its president, Yoweri Museveni, who took the bold decision to speak out publicly about what was considered a shameful disease and tell people how to combat it. Prevention strategies, including the promotion of condoms, were central.

But in the last couple of years, the Ugandan and US governments have shown increasing interest in promoting abstinence and fidelity in marriage, with condoms given out only to those who cannot manage either.

New billboards have appeared in Uganda, signed by the office of the first lady and bearing the logo of USAid - the US development agency. One has a picture of a glamourous, smiling young woman, saying "She's saving herself for marriage - how about you?"

Activists argue that while abstinence until marriage and fidelity inside marriage are admirable concepts, human weakness, prostitution, the subservience of women in African society and the difficulty of changing behaviour dictate that condom use must be at least as well promoted, and condoms must be easily available.

But the condom supply has dried up, say campaigners. According to the US pressure group the Centre for Health and Gender Equity (Change), condoms are difficult to find in the cities, and are unavailable in many rural areas. Change says that the same pattern is beginning to occur in other parts of Africa.

"The crisis in Uganda has been created by the actions - and inaction - of the government of Uganda and the Bush administration, the primary donor for HIV/AIDS programmes in Uganda, and a major force in undermining effective HIV prevention programmes throughout sub-Saharan Africa and central America," said Jodi Jacobson, executive director of Change.

The condom crisis began in October last year, when the president ordered a nationwide recall of the condoms distributed free in government health clinics under the brand name Engabu. It was alleged they were of poor quality.

The government carried out a quality testing programme and all condoms were impounded. Public confidence in the Engabu brand plummeted after negative stories in the press and comments by the first lady about the effectiveness of condoms. New taxes pushed the price up.

The government claims that the original Engabu condoms are now too discredited to be distributed, even though tests have cleared them. They have obtained an emergency grant from the UK's Department for International Development for 20m new, unbranded condoms. When those are finished, they will distribute a new batch of 80m of the Engabu brand, they say.

"There is no condom shortage in Uganda," Vastha Kibirige, coordinator of condom procurement at the ministry of health, told the Guardian newspaper.

"The strategy is to distribute the non-branded ones first, and when we are more sure of particular groups that will not mind