ROME (AP) — The United Nations says the number of chronically hungry people in the world is on the rise again after a decade of declines, citing intensifying conflicts, floods and droughts.

In an annual report released Friday, the U.N. says 815 million people were chronically undernourished last year, 38 million more than the previous year. While the number is still below the 900 million hungry people registered in 2000, the U.N. warns that the increase "is cause for great concern."

The U.N. has said some 20 million people face possible famine in parts of South Sudan, northeast Nigeria, Somalia and Yemen.

The heads of major U.N. agencies warn that without concerted action, the ambitious goal set by world governments to end hunger and prevent malnutrition by 2030 won't be reached.