Nicholas Burns, the US state department's third-highest ranking diplomat, is to resign from his post for personal reasons.
|Burns led the Bush administration's diplomatic efforts |
to impose new UN sanctions on Iran [EPA]
The departure of the Undersecretary of State for Political Affairs was announced by Condoleezza Rice, the US secretary of state, in Washington on Friday.
"He decided it was time for him to retire from the Foreign Service," Rice said in Washington.
Burns is a career foreign service diplomat who has served as the US ambassador to Nato and to Greece, and as State Department spokesman.
George Bush was to nominate the US ambassador to Russia, William Burns, to take over the post, senior US officials told The Associated Press news agency on Friday.
The two Burns are not related.
Nicholas Burns had led the Bush administration's diplomatic efforts to impose new UN sanctions on Iran and tried to negotiate a nuclear deal with India.
Rice said Burns will "continue to work on the Indian file," particularly on the US-Indian nuclear agreement which has yet to be fully implemented.
The deal must clear several hurdles including final approval by the US Congress before it can take effect.
Officials said Burns would work on the agreement for the next few months.
There has also been speculation that Burns may seek an elected office in his home state of Massachusetts.
Burns joined the foreign service in 1983 and worked at posts in the Middle East and Africa before taking over the Russia portfolio at the National Security Council towards the end of the Cold War, during the administration of George Bush senior.
He has been descibed as an experienced and skillful diplomat and has been called the most gifted Foreign Service officer of his generation.
He was confirmed in his post in 2005 after President George Bush won a second term in office.