More than 30 million people around the world are infected with HIV
An international Aids conference has ended with a warning that commitments made by wealthy countries to fund access to HIV treatment may not be met.
The charity Oxfam said there had been an air of complacency from government and UN officials at the Mexico meeting.
In 2005, the G8 industrialised nations set a goal of providing HIV treatment to all who needed it by 2010.
But with less than two years to go, the G8 leaders have committed little more than a third of the promised resources.
Michel Kazatchkine, the head of the Global Fund to fight Aids, tuberculosis and malaria, said that although lives were being saved on an unprecedented scale, he was deeply concerned at the lack of funds.
"We should be deeply concerned that with less than two years to go before our deadline for universal access, the G8 has committed little more than a third of the resources that it has promised to deliver by 2010," said Mr Kazatchkine at the close of the six-day conference.
Millions of lives were at stake, said Robert Fox, the leader of Oxfam International's delegation in Mexico City.
"What we have is the sense of real slippage, that well you know it may not be 2010 and it probably will be 2015, as if that doesn't matter," he said.
Twenty-four thousand people attended the conference, and the organisers said the voices of those who bore the brunt of the HIV-pandemic had been loud and clear.
Mr Kazatchkine highlighted three priorities to take the battle against Aids forward:
- Defeating the discrimination against those with Aids virus flourished
- Focussing research on more coordinated research
- Strengthening health systems in developing nations
The Mexico City conference was the 17th of its kind since acquired immune deficiency syndrome (Aids) emerged in 1981.
The next conference will be held in Vienna in 2010.