Episcopal Archbishop Emeritus of South Africa Desmond Tutu has asked U.S. President Barack Obama to reconsider his decision to cut funding for the President's Emergency Plan for AIDS Relief (PEPFAR) – a move that the bishop says will leave thousands of Africans vulnerable.

"Having met President Obama, I'm confident that he's a man of conscience who shares my commitment to bringing hope and care to the world's poor. But I am saddened by his decision to spend less than he promised to treat AIDS patients in Africa," Tutu wrote on Tuesday in an opinion piece in the New York Times.

Citing from a Harvard research study, Tutu noted the decrease in funding will deny HIV treatment to some 80,000 Africans over the next five years, which will result in 1.2 million "avoidable deaths."

"President Obama's plan to decrease support is deeply distressing; American financing for the fund should be increasing," he said.

Tutu's remarks come following the Obama administration's decision to add only $366 million to the PEPFAR fund – about a third of the $1 million the president had promised during his 2008 campaign.

Other AIDS activists, particularly those in Vienna participating in the 18th International AIDS Conference, have also been critical of the United States' level of contribution, although PEPFAR director Eric Goosby called such criticism unfair, noting that the U.S. still remains as the world's largest donor in the fight against HIV.

"I think it has been frustrating to be presented as a non-contributor. The administration and the president have been hurt by the characterization that the US has not stepped up to the plate and taken this commitment seriously in all arenas," Goosby told the UK Telegraph.

Former President Bill Clinton has also come to the Obama administration's defense, saying on Monday that the president's promises were made before the country felt the brunt of the global economic recession.

"Since then he has tried to keep his commitments," Clinton said. "Even his worst critics admit that he tries to keep his commitments. That's why they don't like him."

Still, some critics, including Tutu, remain unconvinced.

"It is just not reasonable in the state of human priorities to think that [an extra] $1bn [in addition to the expected $1bn donation to the global fund] cannot be raised to confront one of the health tragedies of our times," Stephen Lewis, founder of AIDS Free World, told the Telegraph.

"I appreciate that tough financial times require the United States government to cut spending. But scaling back America's financial commitments to AIDS programs could wipe away decades of progress in Africa," Tutu said.

"Surely the richest country on the planet can find the means to fight this scourge," he added.