WASHINGTON, Sept. 18 — A top House Democrat began an inquiry on Tuesday into accusations that the State Department's inspector general repeatedly interfered with investigations into fraud and abuse in Iraq and Afghanistan, including security defects at the new United States Embassy in Baghdad.

Representative Henry A. Waxman of California, the chairman of the Committee on Oversight and Government Reform, sent the inspector general, Howard J. Krongard, a 14-page letter spelling out accusations made by several current and former employees of Mr. Krongard's office who documented their charges with e-mail messages.

Some of the accusers have sought whistle-blower status, which protects government employees from being punished for reporting possible malfeasance, Mr. Waxman said.

"One consistent element in these allegations is that you believe your foremost mission is to support the Bush administration, especially with respect to Iraq and Afghanistan, rather than act as an independent and objective check on waste, fraud and abuse on behalf of U.S. taxpayers," Mr. Waxman wrote. He invited Mr. Krongard to respond to the accusations at a committee hearing on Oct. 16.