The US Senate passed legislation on Monday to extend for another five years a successful and popular programme to combat AIDS worldwide started 10 years ago by former President George W Bush.

The 100-member Senate approved the measure by unanimous voice vote. It is expected to be considered - and passed - by the House of Representatives as soon as Tuesday before going to President Barack Obama for his signature.

The bill features several provisions to increase oversight of the President's Emergency Plan for AIDS Relief, known as Pepfar. The widely praised programme is considered a catalyst for advancing HIV treatment, particularly in Africa.

It supports almost 6 million people worldwide who are receiving anti-retroviral drugs, and has provided care and support to nearly 15 million people, including more than 4.5 million orphans and vulnerable children.

Among other things, the legislation passed on Monday extends existing funding requirements for treatment of orphans and vulnerable children.

The measure was introduced in the Senate and House by Senators Robert Menendez, Democratic chairman of the Senate Foreign Relations Committee, and Bob Corker, its top Republican; and Representative Eliot Engel, the ranking Democrat on the House Foreign Affairs Committee, and Ed Royce, the panel's Republican chairman.

Aides said they expected it would pass the House because of this bipartisan support. Although the programme is considered one of the most successful US foreign policy efforts in history, its reauthorisation in 2008 was marked by fights over social issues like birth control and abortion rights.

"Extending this vital programme will bolster our efforts to combat HIV/AIDS as Pepfar transitions from an emergency response to a sustainable effort that embraces greater partner country ownership," Menendez said in a statement.

Pepfar funding has fallen 12 per cent since 2010. Critics have accused Obama, a Democrat, of failing to show the same level of commitment to fighting AIDS as his Republican predecessor, Bush, who poured $15 billion into the programme to combat AIDS worldwide.

Obama has argued that his administration has expanded the programme's scope without increasing spending. - Reuters