In a sudden development, US Ambassador to India Nancy Powell has resigned from her post, days after media speculation that she may be shipped out.

"US Ambassador to India Nancy J Powerll announced in a US MIssion Town Hall meeting March 31 that she has submitted her resignation to President Obama and, as planned for some time, will retire to her home in Delaware before the end of May," an announcement in the US Embassy website said tonight.

US Embassy sources did not want to hazard a guess on the decision of the 67-year-old career service officer to quit her post and return home at a time when India is in an election process and Washington is also deeply interested in its outcome.

There was media speculation a week ago that Powell would be replaced with a political appointment as an attempt by the Obama administration to "clean the state" with India.

The report had said Powell had dragged her heels on meeting Gujarat Chief Minister Modi and was perceived as being "too close" to the UPA's foreign policy establishment.

However, when Washington decided to warm upto Modi, perceived as one of the front runners for the prime minister's post, Powell met Modi on  February 13, ending a nine-year-old boycott of the Gujarat leader on the issue of 2002 riots.

The US move  marked a u-turn in its earlier stand of having nothing to do with Modi, whose visa it cancelled in 2005 under a domestic law on the issue  of "severe violations of religious freedom". Ever since it had refused to review its policy.