U.N. Secretary-General Kofi Annan has urged world leaders to follow through on their promises to help stop the spread of AIDS and HIV, the virus that causes AIDS.

In a statement released for World AIDS Day Friday, Mr. Annan called the HIV/AIDS pandemic the greatest challenge of this generation. But he said the international community has finally begun to take the fight against the virus seriously.

U.S. Secretary of State Condoleezza Rice released a statement that the United States mourns the more than 25 million people who have died of AIDS since the first case was reported 25 years ago and remembers the more than 39 million people who are currently living with HIV.

President Bush and the first lady are hosting a meeting on World AIDS Day at the White House Friday.

The president has said marking the event helps underscore U.S. commitment to fight the pandemic with compassion and decisive action.

The United Nations says the virus is the leading cause of death among men and women between the ages of 15 and 59. It says more than four million people will be infected this year, with nearly two out of three new infections occurring in Sub-Saharan Africa.

U.N. officials say infection rates are increasing in Eastern Europe and Central Asia.

Some information for this report was provided by AP and Reuters.