Anti-HIV drugs reached 1.2 million more people last year, the UN announced Monday at the world AIDS forum, as former US president Bill Clinton defended Barack Obama's funding to fight the disease.
The increase meant that 5.2 million people had access to drugs to repress HIV, the virus that causes AIDS, the UN's World Health Organisation said as thousands of delegates met at the 18th International AIDS Conference in Vienna.
"This is the largest increase in people accessing treatment in a single year. It is an extremely encouraging development," WHO's assistant director general Hiroki Nakatani said.
Since 2003 the number of people on anti-HIV drugs has risen 12-fold, the UN health agency said.
But experts say that despite the surge, only roughly half of the world's poor, badly infected people have access to the drugs.
The six-day conference of scientists, policymakers and grassroots workers opened Sunday in Vienna to rowdy protests from activists accusing President Obama of reneging on a campaign pledge to spend some 50 billion dollars on AIDS by 2013.
Some of several hundred protestors chanted "Obama lies - people die," as new data pointed to a slump in AIDS funding.
In a keynote speech on Monday, Clinton defended Obama, laying the blame for financial belt-tightening at the door of the US Congress.
"You have two options here, you can demonstrate and call the president names or we can go get some more votes in Congress to get some more money," Clinton said. "There is no way the White House will veto an increase in funding for AIDS."
At Sunday's opening ceremonies, UN Secretary General Ban Ki-moon warned in a video message that the "significant progress" in the 29-year war on AIDS could be reversed if countries retreated in their funding efforts.
Veteran campaigners also demanded political leaders fund AIDS with the same speed and generosity as they refloated the banking sector in 2008 and shored up the Greek economy earlier this year.
Obama has submitted a 2011 fiscal year request of 5.7 billion dollars for spending on AIDS, almost unchanged from last year and just 236 million dollars more than 2009, the last fiscal year of the George W. Bush administration, according to analysis by the US anti-AIDS organisation amfAR.
"I completely understand why the advocates for greater AIDS funding have loudly protested. But I do not think it is either fair or accurate to say the president has gone back on his promises as if this was a callous walking away," Clinton said.
"When he signed that petition saying he would support greater AIDS funding, it was before the American economy led the world into the worst financial crisis since the depression.
"Since then, he has tried to keep his commitments... even his worst critics admit that he tries to keep his commitments, that's why they don't like him," he said.
Figures released on Sunday showed that funding by rich countries slipped in 2009 as the economic recession bit.
The widening gap threatens the goal of providing universal access to AIDS drugs and may even disrupt supplies to those already on the lifeline therapy, say some experts.
From 2002 to 2008 donations from rich economies for poor countries rose from 1.2 billion to 7.7 billion, but fell back last year to 7.6 billion, according to an analysis by the Kaiser Family Foundation and UNAIDS.
That left a funding shortfall last year of more than seven billion dollars.
For 2010, 25 billion dollars has to be mustered for fighting AIDS in poorer countries, according to a previous UNAIDS estimate. So far, there is a funding shortfall of 11.3 billion.
At least 25 million people have died of acquired immune deficiency syndrome (AIDS) since the disease first came to light in 1981.
At the end of 2008, more than 33 million people had HIV, and 2.7 million people that year became infected, according to UNAIDS last year.