The head of the United Nations refugee agency issued an urgent appeal Sunday for funds to help the victims of what he described as the “worst humanitarian disaster” in the world – the drought in Somalia.

UNHCR chief Antonio Guterres called for “massive support'' for the thousands of refugees who cross the borders of Kenya and Ethiopia every day from Somalia.

Guterres visited the Dadaab refugee camp in Kenya that now is home to more than 380,000 Somalis. Guterres is on a tour of the region to highlight the dire need. On Thursday, he was in the Ethiopian camp of Dollo Ado, which is also overflowing.

U.N. officials say every day about 1,400 Somali refugees cross into Kenya, and 1,700 into Ethiopia.

The epicenter of the drought lies on the three-way border shared by Kenya, Ethiopia and Somalia, a nomadic region where families heavily depend on the health of their livestock. Uganda and Djibouti have also been hit.

The refugee agency is seeking $136 million in aid to combat the crisis.