Michel Kazatchkine, executive director of The Global Fund, said his organization had not yet "felt the pinch" from recent financial turbulence or rising energy and commodity prices.

But he told Reuters on Tuesday he was "very concerned" the economic downturn might have a negative impact on future pledges to groups such as The Global Fund - launched by the Group of 8 industrialized nations to fight AIDS, tuberculosis and malaria.

"Maybe it is a little too early to see the true consequences of the global downturn. But I am truly concerned and the world should be concerned about how we can meet our development goals," Kazatchkine said.

"The heads of health and aid agencies had the opportunity to speak with the secretary general of the United Nations recently and our main concern expressed to him was about the decrease in overseas development aid (ODA), particularly in health."

The Global Fund has raised about $10.8 billion since 2002 to combat major diseases, taxpayers in the United States, Japan and Europe footing most of the bill.

Kazatchkine was in Brussels to meet European Union development ministers before the July G8 summit in Japan, where The Global Fund will ask leaders of the richest nations to deliver on their promises to the world's poorer countries.

"Our message to the G8 is about keeping with the commitments. The G8 agreed to having an annual review on where they stand with their commitments and where they should go, notably in health," Kazatchkine said.

The Global Fund estimates that around 6 million people die every year from AIDS, tuberculosis or malaria.

"Our message to the G8 is that investment in health is paying off with less mortality and we are seeing spectacular results in all three areas," Kazatchkine said.

"Sustainability is the key to solving this problem long term. We have seen a drop-off in pledges going into the long term, so we will also be sending a message that we need long term financial backing if we are to achieve what we set out to do."