The U.S. State Department has announced the resignation of Randall Tobias as the head of two foreign aid programs.

The department cited "personal reasons" for the decision, but U.S. news reports say Tobias abruptly resigned after his name was connected to an escort service that is under federal investigation.

Tobias served as director of the U.S. Agency for International Development (USAID) and as director of U.S. foreign assistance.

On Thursday, Tobias told reporters from the U.S. television network ABC that he had been a customer of a Washington-based escort service whose owner has been charged with running a prostitution business.

Rice appointed Tobias to the two posts in 2006.  Previously, he was the top advisor for the government's HIV/AIDS policies.

Some information for this report was provided by AP.