Sarna, an Indian Foreign Service officer of the 1980 batch, was serving as secretary (west) in the ministry of external affairs before he was posted in London in January. He succeeds Arun Singh, who is due for retirement.
The 59-year-old diplomat was among the longest-serving spokespersons of the MEA. He had held the post between 2002 and 2008.
"He is expected to take up the assignment shortly," the external affairs ministry said.
Government has also appointed 1988-batch IFS officer Taranjit Singh Sandhu as the next High Commissioner of India to Sri Lanka. He will replace Yash Sinha.
In Washington, Sarna's main task will be to ensure continuity in Indo-US relations when a new dispensation takes charge.
Sarna has authored many fiction and non-fiction books, with the most recent being 'Second Thoughts: On Books, Authors and the Writerly Life' released last year. He was also India's Ambassador to Israel from 2008 to 2012.
For two years from August 2012, Sarna had served as additional secretary in-charge of international organisations in the MEA.
Sarna had served at various Indian missions including in Moscow, Warsaw, Tehran, Geneva, Thimphu and Washington.
Yash Sinha, tipped to be Indian High Commissioner to the UK, is a seasoned diplomat and, in his career spanning 35 years, he has handled several important assignments at the MEA and in Indian diplomatic missions in South Asia, the Middle East, Europe and South America.
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