African nations whose populations have been devastated by AIDS have made big strides in fighting HIV, with new infections down 25 percent since 2001 in some of the worst hit places, a U.N. report said on Friday.

African countries with the biggest epidemics like Nigeria, South Africa, Zambia and Zimbabwe are leading the decline, thanks to better use of prevention methods and greater access to life-preserving drugs, the United Nations AIDS program (UNAIDS) report said.

For the first time change is happening at the heart of the epidemic, executive director Michel Sidibe said in a statement. The report charts progress toward a globally agreed Millennium Development Goal to halt and start to reverse the spread of AIDS by 2015.

Sub-Saharan Africa remains the region hardest hit by HIV, accounting for 67 percent of all people living with the virus worldwide, 71 percent of AIDS-related deaths and 91 percent of all new infections among children.

The report said that between 2001 and 2009, new HIV infections fell by more than 25 percent in 22 countries in sub-Saharan Africa.

However, Sidibe warned that a $10 billion shortfall in the funding for AIDS in 2009 could put further progress at risk.

UNAIDS said an estimated $15.9 billion was available for the global AIDS response, which is $10 billion short of the estimated need.

Although the number of new HIV infections is steadily falling or stabilizing in most parts of the world, the report said major problems still existed in certain regions and among particular high risk groups.

Eastern Europe and Central Asia have rapidly expanding HIV epidemics -- the disease is spreading in that region at a rate of 500 new infections a day -- and in several high-income countries there has been a resurgence of HIV infections among gay men.

World leaders are due to meet in New York next week to take stock of the Millennium Development Goals, which were agreed a decade ago and aimed at drastically reducing poverty and hunger.

UNAIDS said access to treatment for the human immunodeficiency virus (HIV) -- an incurable viral infection that causes AIDS and infects around 33.4 million people around the world -- has increased 12-fold in six years, and 5.2 million people are now getting the drugs they need.

But another 10 million who need AIDS drugs don't get them.

To sustain the gains we are making, further investments in research and development are needed -- not only for a small wealthy minority, but also focused to meet the needs of the majority, Sidibe said.

UNAIDS recommends national governments allocate between 0.5 percent and 3 percent of government revenue to HIV and AIDS, depending on the prevalence of disease in their country.

The report said that while domestic investments in AIDS have increased over the past decade, for a majority of the countries severely affected by the disease, those would not be enough to meet their needs.