The United Nations says the number of young children in Somalia expected to suffer severe acute malnutrition this year has risen to more than half a million.

The prediction is at a higher level than in 2011 when famine killed tens of thousands of Somali children.

A Unicef spokesman, James Elder, called the situation a "pending nightmare".

He said 700 children died in nutrition centres last week, and facilities across the country were full.

Somalia and the wider Horn of Africa region have suffered five years of below average rainfall.