Nancy Powell during Indian prime ministerial candidate Narendra Modi's home last month. Pic: AP.

NEW DELHI (AP) — The U.S. ambassador to India says she has submitted her resignation to President Barack Obama and will retire before the end of May.

Ambassador Nancy Powell did not give any reasons for her decision, but said she had planned it for some time.

According to the U.S. Embassy web site, Powell announced her resignation in a U.S. Mission Town Hall meeting in New Delhi on Monday and said she would retire to her home in Delaware.

She took up her posting in New Delhi two and a half years ago.

She is ending a 37-year career that has included postings as U.S. ambassador to Uganda, Ghana, Pakistan, Nepal and India.