Kenzo Oshima, a Japanese career diplomat, has been appointed as U.N. undersecretary general in charge of humanitarian affairs and relief operations, the United Nations announced Wednesday.

Kenzo Oshima

Oshima, 57, who currently oversees international peacekeeping and humanitarian assistance operations from the Prime Minister's Office in Tokyo, will assume his new post in mid-January.

The post is currently held by Sergio Vieira de Mello, who serves as the U.N. special representative in East Timor, a post he will retain.

Oshima is the fourth Japanese to become a U.N. undersecretary general. The others include Yasushi Akashi, ex-U.N. special representative in Cambodia, and Kensaku Hogen, head of the U.N. public information department.