EVIAN, France -- European Commission Chief Romano Prodi questioned on Sunday how much of U.S. president George W. Bush's $15 billion pledge to fight AIDS would turn into new cash to spend battling the disease.

Bush's plan, signed into law last week, sets out a spending framework for $15 billion over five years, but the U.S. Congress must still authorise putting any cash into the pot.

"The money's not on the table," Prodi told Reuters, adding that much of the U.S. cash would be earmarked for bilateral accords.

Speaking at the G8 summit of world leaders, Prodi said only $1 billion from Bush's plan would remain for the global fund to fight AIDS, malaria and tuberculosis, set up two years ago to fight the killer diseases.

Prodi insisted European Union payments remained higher than Washington's to the war chest, which is already suffering a shortfall in pledges.

"It was really easy for me to match it, it's certainly not a problem because we are giving more than that (already)," Prodi told reporters when asked if the EU would match U.S. commitments to the fund.

The three-disease war chest was set up by the G8 countries in 2001 to channel cash directly to people affected by the illnesses, which kill some six million people each year.

French President Jacques Chirac also put the new U.S. commitments at worth an annual $1 billion of cash for the fund.

But he insisted the EU still had some way to go in coming up with a total $1 billion to match the U.S. money.

France would take the lead in tripling its own contribution from $50 million to $150 million from 2004, he said, throwing down the gauntlet to other members of the European Union.

"I hope we shall be followed (by other EU countries)," he told a news briefing, adding he hoped for firm pledges at an EU summit in Greece later this month. "I have a feeling, a sense that Europe will take up the challenge, in other words that it will come up with its $1 billion as well."

UN Secretary General Kofi Annan has championed the fund, but despite initial pledges from rich countries topping $2.0 billion only $1.5 billion has come in.

Britain promised on Friday it would give an additional $80 million to the fund, making its contribution $280 million through to 2008.