U.N. Secretary-General Kofi Annan has warned of growing desertification, saying it will further worsen problems stemming from poverty.

On the occasion of World Environment Day Monday, he said global poverty, unsustainable land management and climate change have sped up desertification.

The world body has designated this year's World Environment Day as Desert and Desertification Day.

A U.N. report said that from Africa's Sahara Desert to China's Gobi Desert, deserts account for a fifth of the world's land surface and that other regions are on the verge of turning into deserts.

The 1972 U.N. General Assembly designated June 5th as World Environment Day to commemorated the U.N. Environment Summit in Stockholm the same day.