The foreign minister said Thursday that it was unacceptable that the Indian ambassador to the United States was patted down by a security agent at a Mississippi airport, and that he would complain to Washington. The ambassador, Meera Shankar, left, was returning from giving a speech at Mississippi State University last week when she was pulled out of line at the airport and given a pat-down by a female Transportation Security Administration agent. Foreign Minister S. M. Krishna said this was the second time the ambassador had been chosen for a pat-down in the past three months. â€œLet me be very frank that this is unacceptable to India,â€ he said. A T.S.A. spokesman said that diplomats were not exempt from searches, and that bulky clothing could prompt a pat-down. Secretary of State Hillary Rodham Clinton said the State Department was looking into the matter.