U.S. authorities are investigating a former American ambassador who until last month was advising the State Department on civilian aid to Pakistan.
The Washington Post first reported Thursday that authorities last month searched the Washington home of Robin Raphel.
According to the newspaper, the Federal Bureau of Investigation is leading a counterintelligence probe of the 67-year-old career diplomat.
The exact nature of the investigation remained unclear but the Post cited two U.S. officials as saying it was a counterintelligence matter, which usually involves spying allegations.
The newspaper quoted a spokesman for Raphel as saying she had not been told that she was a target of the probe but that she was cooperating. No charges have been filed.
A State Department spokeswoman acknowledged the investigation but declined further comment, the Post said. Raphel did not respond to the Post's requests for comment.
The newspaper said Raphel was a senior adviser on Pakistan for the State Department in a job responsible for administering non-military aid, such as economic grants and incentives.
U.S. State Department officials confirmed that Raphel's security clearance was pulled in October, ending a contract she had with the government agency.
Raphel served as ambassador to Tunisia from 1997 to 2000 and was the assistant secretary of state for South and Central Asian Affairs under former U.S. President Bill Clinton.
She retired from the diplomatic corps in 2005 after 30 years and went on to work as a contractor with the U.S. Embassy in Islamabad in 2009.
Most recently, Raphel worked in Washington in the State Department's office of the U.S. Special Representative to Afghanistan and Pakistan.