The head of the UN mission to the Democratic Republic of Congo is to leave his post.
Top envoy William Lacy Swing will be replaced by a new special representative later in the year.
The UN mission in DR Congo has faced criticism after allegations that UN peacekeepers sexually exploited refugees in their care.
UN spokesman Fred Eckhard said Mr Swing would remain in the job for the time being to allow for a smooth transition.
Violence has flared in the turbulent north-eastern Ituri region of Congo, where the UN has one of its largest missions, with more than 13,000 troops. In late February, nine Bangladeshi peacekeepers died when they were ambushed whilst on patrol in the area and, on Tuesday, 50 militiamen were killed during a UN operation against the militia in the same area.
"The secretary general noted that Mr Swing evidently had his hands full across all these fronts and would need to show strong leadership in all these areas," Mr Eckhard said.
Last month, a UN team investigated 72 allegations of abuse by UN peacekeepers and civilian staff.