Image copyright Reuters Image caption Nancy Powell, shown welcoming then-US defence secretary Leon Panetta to India in 2012, leaves after a long career in the US foreign service

The US ambassador to India has resigned and will leave her post by the end of May, the embassy in New Delhi has said.

Nancy Powell has been ambassador since 2012, after postings as ambassador to Uganda, Ghana, Pakistan and Nepal.

The state department said she would retire to her home in Delaware and had planned the move for "some time".

The move comes after a row between the US and India over the arrest and brief jailing of an Indian diplomat in New York on a visa fraud charge.

Devyani Khobragade, an official in the New York consulate, was accused of underpaying her housekeeper and lying about it on immigration forms. She has left the US.

Analysis The arrest of Devyani Khobragade in December triggered a furious response in India, exposing deep misunderstandings between two states who were supposedly becoming closer allies. Relations have still not fully recovered. One Indian newspaper recently reported that the Obama administration was planning to replace Nancy Powell as part of an attempt "to clean the slate", citing US and Indian sources. An Indian foreign ministry official had no comment on the US ambassador's resignation but said "there are still issues to be resolved" between the two countries.

A state department spokesman would not say if Ms Powell's resignation was linked to the row or to the upcoming general election in India.

The Hindustan Times reported last week Ms Powell might be replaced as the US envoy.

State department spokeswoman Marie Harf said in a Monday news conference the move was "in no way related to any tension, any recent situations, there is not any big behind-the-scenes story here".

Ms Harf said any rumours and speculation to the contrary were "totally false".

In statement from the US embassy in India, Ms Powell "expressed her appreciation for the professionalism and dedication of the US mission to India team".

"She also thanked those throughout India who have extended traditional warm Indian hospitality to her and who have supported stronger bilateral ties," the statement said.