The Bill and Melinda Gates Foundation said Thursday it will give an additional $50 million to the United Nations’s global fund to fight AIDS, a day after the United States said it won’t give the resource-short charity any more money.

The Gates Foundation’s announcement at the International AIDS Conference raises its contribution to the Global Fund to Fight AIDS, Tuberculosis and Malaria to $150 million.

“The Global Fund is an extraordinary model for financing the fight against AIDS, TB and malaria,” said Helene Gayle, director of the foundation’s HIV program.

“We urge governments, the private sector and other donors to dramatically increase their contributions to the Fund. Their generosity can help save millions of lives,” she said during a special screening of “46664: The Message,” a film honoring South African democracy icon Nelson Mandela.

46664 was the number of Mandela’s prison cell when he was incarcerated on Robben Island during the apartheid era. Mandela is attending the last two days of the AIDS conference, which ends Friday.

The Seattle-based Gates foundation is led by William H. Gates, the father of the Microsoft founder, and Patty Stonesifer.

The Global Fund, set up 30 months ago, faces a major funding gap. Donors have committed a total of $3.4 billion through 2004, enough to meet its needs through the end of the year, but pledges for 2005 through 2008 are just $2 billion, far below the $3.6 billion that the Fund projects it will need in 2005 alone.

On Wednesday, U.S. Global AIDS Coordinator Randall Tobias rejected a call by the U.N. Secretary-General Kofi Annan for a $1 billion contribution in 2005, saying the money it has already given is sufficient. The United States has given about $580 million to Global Fund until now, and has proposed giving another $200 million for 2005.

“I think that’s going to be more than adequate to meet the requirements of Global Fund in terms of getting the money out doors and programs in place,” Tobias said in an interview.

So far, the Fund has approved nearly 300 grants for projects in 128 countries, and hopes to provide antiretroviral treatment to more than 1.6 million people over the next five years. Some 38 million people are infected with HIV/AIDS worldwide.