President Obama speaks at a World AIDS Day event in the Eisenhower Executive Office Building, near the White House in Washington, D.C., Dec. 2, 2013. (Shawn Thew/EPA)

President Obama pledged Monday to give up to $5 billion to the Global Fund to Fight AIDS, Tuberculosis and Malaria over the next three years, saying that an “AIDS-free generation” may be within reach.

The pledge represents $1 billion more than the United States committed during the previous round of funding in 2010, when Obama faced criticism for not doing enough and setting a bad example that gave other countries an excuse to limit their donations. The $5 billion contribution — which is the amount activists requested — will be delivered if other countries commit to giving $10 billion under a funding ratio set by Congress.

“We’re making progress,” Obama said at a White House event marking World AIDS Day, which was Sunday. “But we’re all here today because we know how much work remains to be done.”

Britain, Canada, Denmark, France, Germany and Sweden announced separately that they had raised their contributions to the Global Fund, which was created in 2002 to coordinate international efforts to fight infectious disease in low-income countries. It provides more than 20 percent of resources for HIV treatment and prevention.

The announcements represent a redoubling of global efforts to fight AIDS. Despite billions spent on research in the 34 years since the disease was recognized, a vaccine has eluded scientists, and efforts to stop the spread of the illness through preventive measures — such as microbial gels — have been unexpectedly challenging. One million Americans are living with AIDS today.

“We need to keep focusing on investments to communities that are still being hit hardest, including gay and bisexual men, African Americans and Latinos,” Obama said in his remarks. “We need to keep up the fight in our cities, including Washington, D.C., which in recent years has reduced diagnosed infections by nearly half. And we’re going to keep pursuing scientific breakthroughs.”

He added, “We will win this battle, but it is not over yet.”

In announcing the additional funding, White House officials outlined a multipronged approach to fighting AIDS.

On the research front, the National Institutes of Health will redirect $100 million to advance the study of new-generation therapies to develop a cure for HIV. And Health and Human Services Secretary Kathleen Sebelius said the rollout of the Affordable Care Act would make it possible for all pregnant women in the United States to be screened for HIV, as is recommended by the U.S. Preventative Services Task Force.

Obama has been under pressure in recent months from U.S. lawmakers and activists and public health leaders worldwide to do more to fight the global pandemic. In early November, a bipartisan group of 40 lawmakers urged him to double support for the President’s Emergency Plan for AIDS Relief, a program strongly supported by former president George W. Bush that has provided treatment for millions of HIV-positive people in Africa. Bush put $15 billion into the program, but U.S. funding has fallen since his tenure.

Private sources have made up some of the shortfall over the years, primarily the Bill & Melinda Gates Foundation, which on Monday pledged to give up to $500 million in additional matching money to the Global Fund.

The foundation, run by the Microsoft co-founder and the world’s richest man, has contributed a total of $1.4 billion to the global program. The largest chunk — $750 million — was donated last year as an emergency measure to keep AIDS drug programs afloat as support from governments dwindled amid the economic downturn.

Since it was founded in 1997, the Gates Foundation has become one of the most influential players in global health care, disbursing 17 percent of the world’s funding for research and development. The NIH provides 36 percent.

In an interview with a small group of reporters and NIH Director Francis S. Collins on Monday morning, Bill Gates said that his foundation is matching donations from private sources, such as a recent auction in New York that brought in $13 million and a $65 million donation from a philanthropist in Indonesia.

“We’re encouraging new types of people to get in,” he said.

Gates said it’s important to fund both the biomedical side and the “delivery side” — the role played by the Global Fund in taking new treatments to communities.

“If you want to get scientists to discover things, they have to see that there is money for it to be delivered,” Gates said. “Otherwise there’s no reason to do the discovery.”

Zachary A. Goldfarb contributed to this report.