With the Nigerian president and the United Nations secretary-general at his side, President Bush on Friday pledged $200 million -- and promised more money later -- for fighting AIDS and other diseases ravaging Africa.

The U.S. pledge is seed money for a $7 billion to $10 billion fund that U.N. Secretary General Kofi Annan hopes the world's richest nations and private philanthropists will establish to fight AIDS, malaria and tuberculosis. Annan also is trying to drum up support for an international action plan to be adopted at a June 25-27 special session of the U.N. General Assembly.

"Across the world at this moment there are people in true desperation and we must help," Bush said during a Rose Garden ceremony.

Activists sniffed at Bush's promise for future funding and called the $200 million a pittance. A hodgepodge of protesters milled in front of the White House gate, chanting, "Billions for Star Wars, chump change for AIDS," a reference to the missile defense system Bush has said he wants.

"In the face of what will soon be the worst plague in human history, it's tragic that the richest country in human history is unwilling to contribute its fair share to finance the solution," said Salih Booker, executive director of the nonprofit advocacy group Africa Action.

Even Annan and Nigerian President Olusegun Obasanjo gently prodded for more.

"As we declare global war on AIDS, we will need a war chest to fight it," Annan said. "We need a response that matches the challenge."

Obasanjo estimated that $7 billion to $8 billion will be needed each year "to make an impression" on the epidemic. "But, with this beginning, and just the beginning, ... I thank you on behalf of all AIDS sufferers in the world, but particularly on behalf of all AIDS sufferers in Africa," he told Bush.

Harvard University economist Jeffrey Sachs said the size of the initial donation was not as important as the fact that it represents a new approach to fighting AIDS.

"There is no doubt in my mind that the $200 million is not sufficient. And there is no doubt in my mind that there will be more money to come," Sachs said, adding that the global fund will "raise the magnitude of the battle in a very important way."

Bush said the funds were "a founding contribution" outside of $760 million the United States was spending this year on international AIDS efforts, and billions devoted to AIDS research. He said the United States would give more "as we learn where our support can be most effective." Bush noted that 11 million African children have lost their parents to AIDS.

"In a part of the world where so many have suffered from war and want and famine, these latest tribulations are the cruelest of fates," Bush said. "Only through sustained and focused international cooperation can we address problems so grave, and suffering so great."

House Minority Leader Dick Gephardt, D-Mo., cheered Bush's announcement but encouraged the president to put sufficient federal resources into fighting AIDS immediately. America "has an obligation to lead this effort, we have the resources and now we must muster the will to devote them to this problem," he said.

Since the vast majority of people suffering from infectious diseases who cannot afford treatment are in Africa, the continent is expected to get a large share of the funds. Of 36 million people around the world infected with HIV, roughly 26 million live in Africa.

Secretary of State Colin Powell will travel to Africa on May 22 to see the AIDS problem firsthand. He was to stop in Mali, South Africa, Kenya and Uganda.

Friday's announcement came while Bush, by greeting Obasanjo, held his first meeting with an African president. Bush said they discussed Nigeria's plans to increase oil production, a move called "positive news for U.S. consumers" expecting to be squeezed by exorbitant fuel prices this summer.

They also talked about U.S. support for Nigeria's efforts on peacekeeping and conflict resolution in places such as Angola, Congo and Sierra Leone. "The short of it is that Nigeria is a friend of America, and the president is a friend of mine," Bush said.

"I now can feel that if there is any need to call on President Bush, he knows what I look like," Obasanjo said.