The results of a second study shocked scientists when they proved that the gel, developed by researchers at the University of KwaZulu-Natal, could not, after all, save millions of lives.

The Centre for the Aids Programme of Research in SA last year found that the gel was 39% successful in preventing HIV infection. Its development was hailed as a breakthrough in reducing women's risk of contracting HIV.

But the researchers leading the study, Vaginal and Oral Interventions to Control the Epidemic, at 15 sites in South Africa, Uganda and Zimbabwe, yesterday recommended that the 5000 women who participated in the study should stop using the gel because it is ineffective.

And in more bad news ahead of World Aids Day on December 1, Doctors Without Borders, the Treatment Action Campaign and other groups fighting the pandemic raised concerns about the dramatic reduction in the global financial commitment to fighting the disease.

As UNAids pushes for South Africa to double its antiretroviral treatment coverage by 2015, the global financial crisis has led many countries to renege on their funding promises, spelling disaster for states whose HIV programmes depend almost entirely on donor support.

Health Minister Aaron Motsoa-ledi will release the latest HIV prevalence statistics today . South Africa's HIV prevalence was 29.4% in 2009 and 29.3% in 2008.

Professor Salim Abdool Karim, director of the Aids research centre, said he was "baffled" by the results of the new study. "This is totally unexpected because there was good evidence from laboratory research, animal studies and human trials, which showed that Tenofovir gel prevented HIV."

Karim and his wife, Quarraisha Abdool Karim, were widely lauded after the gel was presented at the International Aids Conference, in Vienna, UNAids and the Joint UN Programme on HIV/Aids last year.

It was there that the global microbicide research community agreed that a second study was needed to confirm the protective effects of the gel.

The Karims had been expecting to have the gel in clinics next year but the new findings have sent them back to the drawing board.

"The new development is a setback and a grave disappointment. However, we will continue with our research to find out what went wrong," Karim said.

"The [latest] study was not trying to confirm or undo the Caprisa 004 result. But it's a real setback."

Karim said it was not known whether the new study's unexpected result was due to inadequate or poor use of the gel by the women participating in the study, insufficient drug levels in women at the time of HIV exposure, or to some other reason.

"As mentioned in previous microbicide studies, to be able to demonstrate the effectiveness of a microbicide gel, women have to consistently use the right amount of the drug to get the right drug levels in the right cells at the right time," he said.

Karim said there were high hopes that the gel would be a significant development in blocking the virus but science did not always "produce the results everyone hopes for".

The setback comes as the Global Fund, which redistributes money from donor countries such as the US, Germany and Italy to countries with a high HIV, TB and malaria burden, said it had put all funding applications for this year on hold because of "resource constraints".

Italy has not paid what it promised, Germany has delayed payment and Belgium, the Netherlands and other European Community countries scaled down their contributions, said Doctors Without Borders spokesman Borrie la Grange.

Section 27 spokesman Daygan Eager said 20% of South Africa's HIV spending was of money from the Global Fund and other donor bodies. "This will have a significant effect on treatment and service delivery," he said.

The TAC's Nokhwezi Hoboyi said the government should take the lead in urging international donors not to pull out of the Global Fund.

Countries such as Malawi, which rely on donations for 98% of its HIV budget, are worried.

Safari Mbewe, spokesman for the Malawi Network of People Living with HIV/Aids, said antiretroviral treatment in his country "can't be guaranteed".

"The future is very uncertain," he said. Though 1.6million South Africans are being treated, that is only 37% of the people who should be taking antiretrovirals.

• The TAC said last week that it faced possible closure in January after it failed to receive a R6.5-million grant from the Global Fund in July, due to ''poor administration'' by the health department. The department denied the TAC would close and blamed the delay on issues with the group's financial report.