UNITED NATIONS (Reuters) - United Nations Secretary-General Antonio Guterres is set to name senior British foreign aid official Mark Lowcock as the new U.N. aid chief, U.N. officials and diplomats said on Wednesday.

Lowcock, who currently heads Britain’s Department for International Development, will replace Stephen O’Brien, who was appointed by previous U.N. chief Ban Ki-moon in March 2015. Lowcock has worked for the British aid department since 1985.

The appointment, due to be announced this week, comes as the world body struggles to help some 20 million people who risk starvation in Nigeria, Somalia, South Sudan and Yemen and fights to get aid into other conflict zones such as Syria and Iraq.