The UN's special advisor on Yemen, Jamal Benomar has resigned, a UN spokesman said.
The envoy resigned on Wednesday night as he "expressed an interest in moving on to another assignment," Xinhua news agency quoted the spokesman as saying.
"A successor shall be named in due course."
"Until that time, the UN will continue to spare no efforts to re-launch the peace process in order to get the political transition back on track," the spokesman added.
Benomar, a Moroccan diplomat, has been acting as a mediator in talks among rival political groups in Yemen since 2011.
His resignation comes as the war in Yemen intensifies, with the Saudi Arabia-led coalition continuing its air campaign against Houthi rebels in the country.
