The UN secretary general, Kofi Annan, yesterday said the Aids epidemic was accelerating on every continent.
Speaking at a UN conference in New York, he warned that only 12% of the people who needed anti-retroviral therapies were getting them.
Mr Annan called for more money and more vocal leadership in the fight against Aids, and said efforts to combat it had so far not "matched the epidemic in scale".
Peter Piot, the head of the UN campaign to tackle the disease, said containing Aids by 2015 might not be a realistic goal, and added that its spread was outpacing many countries' prevention efforts.
However, the day-long UN conference noted some progress, including signs of success in Africa and a vast worldwide increase in the number of people receiving Aids counselling and testing.
Although some countries were capable of halting the spread of the disease over the next decade, efforts to control it in regions including eastern Europe and central America were failing, Dr Piot said.
"What we are faced with is multiple epidemics, and the epidemic is still expanding," he added. "We are actually still moving into the globalisation of the Aids epidemic."
His remarks were one of the few occasions on which a UN official had admitted that at least one of the millennium development goals - a set of aspirations to be met by 2015 which were laid out by world leaders in 2000 - would probably not be met.
The interim UN conference was held to review progress on meeting targets set at a UN general assembly special session on HIV/Aids in 2001.
Dr Piot told the meeting that some success was evident in Africa, citing a decline in the number of new HIV infections among young people in Kenya, Ethiopia, Rwanda, Malawi, Zambia and Uganda, where people were more educated and prevention programmes had begun.
However, he said the $8bn (Â£4.4bn) being spent to combat Aids this year must be doubled to between $14bn and $16bn annually to meet a $7-$8bn shortfall.
He urged leaders to treat the fight against the disease with the same seriousness with which they handled security issues, and said there was a need for a "quantum leap in commitment" because of the huge funding gaps that remained.
Delegates at the conference were urged to provide not only more but also consistent funding, so that people with the disease would know that their treatment would not be cut off because of a lack of cash.
They also discussed research into Aids vaccines and microbicides - gels or creams that women could use to kill the HIV virus during sexual intercourse. "The only possibility we have to stop the pandemic is to boost the research and development of vaccines and microbicides," Humberto Costa, the Brazilian health minister, said.
Gareth Thomas, the undersecretary of state for international development, said it was realistic to believe that a microbicide could be developed in five or six years, while a vaccine was 20 years away at best.
Mr Thomas said he hoped the conference would be a way to "rebuild the political momentum" to get more money for aid and debt relief to poor countries struggling with Aids. "There have been a number of encouraging signs," he told Guardian Unlimited. "There are more donors giving money, and the numbers getting treatment are steadily increasing."
Referring to the World Health Organisation's target of getting 3 million people onto retroviral treatment by the end of this year, he said: "We're not going to achieve that target by 2005, but we're not far away.
"We have to increase the amount of aid. We have to use the G8 and the EU presidency to meet that shortfall of $8bn."
He said the British government was also supporting health systems in developing countries, adding: "The key thing the international community should do is make more money available."
Jean Ping, the president of the general assembly, called on participants - including 36 ministers - to make recommendations to a summit of world leaders in September which will focus on implementing the UN development goals.
Mr Annan said halting the Aids epidemic was a prerequisite for meeting all the other goals. "Only if we meet this challenge can we succeed in our efforts to build a humane, healthy and equitable world," he said.
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() AIDS-Orphans Whitepaper - http://wohcraj.free.fr/aids-orphans
() traductions sur le sida: http://citation.thread.free.fr/sida