The U.N. refugee agency says Africa's refugee population declined last year, as tens of thousands of people returned to their home countries.

The agency's annual report, released to mark World Refugee Day Wednesday, said the main countries of return in Africa were Liberia, Burundi, Angola, Sudan and the Democratic Republic of Congo.

It estimates at least 40,000 refugees returned to each of these countries, most of them voluntarily. Liberia received the largest influx with 108,000 people.

The agency says that overall, Africa had about 2.4 million refugees in 2006, a drop of 150,000 from 2005.

Tanzania continues to host the continent's biggest refugee population - more than 540,000 - followed by Chad, Uganda, Kenya and the DRC.

The biggest source countries for African refugees were war-torn Somalia which has produced more than 460,000 refugees, the DRC, and Burundi.

The refugee agency also noted that several African countries have large populations of internally displaced people, forced from their homes by war or unrest. These include the DRC, Ivory Coast, Somalia, and Sudan.

On Tuesday, Tanzania's President Jakaya Kikwete appealed to the estimated 150,000 Burundian refugees living in his country to return home. He said the refugees no longer have a reason for living in Tanzania now that Burundi's civil war is over.