President George W. Bush at a White House ceremony Wednesday signed into law a bill to reauthorize and expand his HIV/Aids aid program, viewed by many as one of the major achievements of his presidency.

Bush called the program "the largest commitment by any nation to combat a single disease in human history."

The President's Emergency Plan for Aids Relief (Pepfar) reauthorization program calls for a total of U.S. $48 billion to be spent on health initiatives over the next five years -- $39 billion on the fight against HIV/Aids (more than double the amount for that purpose in the original 2003 legislation), $5 billion for the President's Malaria Initiative and $4 billion to fight tuberculosis.

The administration says that Pepfar to date has provided anti-retroviral drugs (ARVs) to more than 1.7 million people, the vast majority in Africa, up from 50,000 people when the plan was enacted in 2003. The new law is expected to provide ARVs to about three million people.

"HIV/AIDS is still one of the world's greatest humanitarian challenges, no question about it," Bush acknowledged in his comment, adding: "It is a challenge we're meeting, and a lot of it has to do with Pepfar."

The law passed with broad bipartisan support but nevertheless took months to win passage. The House of Representatives passed a $50 billion reauthorization bill in April, more than the $30 billion President Bush proposed in his State of the Union address in January.

A group of Republican senators, however, initially blocked its passage, protesting the removal of a clause that required a minimum of 55 percent of spending be directed to treatment. A Senate compromise reached in June directed half of the HIV/Aids funds to treatment and care and also required $2 billion to be spent on programs directed to Native Americans in the United States.

The new Pepfar program dropped a requirement that one-third of the funding be spent on abstinence-only education. However, it does require close monitoring of the program's performance. The Senate also added a measure that would end a ban on issuing visas to persons with HIV/Aids.

Last week, the compromise overwhelmingly passed both the House of Representatives and Senate, clearing the way for Wednesday's signing ceremony. Bush was joined for the ceremony by a bipartisan group of legislators from Congress, including Joseph Biden (Democrat-Delaware), a frequent critic of the president, who called Pepfar "the single most significant thing the president has done," according to the Associated Press.

Pepfar was also praised in a statement by Nancy Pelosi (Democrat-California), the speaker of the House of Representatives. She said the program "will move us from the emergency phase to the sustainability phase."

The measure won support from both major U.S. presidential candidates, Senators John McCain (Republican-Arizona) and Barack Obama (Democrat-Illinois).