WASHINGTON — Senator Kerry yesterday called for an investigation into security weaknesses in the Defense Department’s surplus sales that have let buyers for Iran and China acquire aircraft parts and other valuable military gear.

The Democrat of Massachusetts sought an inquiry by the Senate Foreign Relations Committee after the Associated Press reported that in several instances, middlemen for the countries had exploited security flaws to acquire sensitive surplus. The surplus sales include parts for F-14 “Tomcat” fighter jets, a plane retired last year by America and now flown only by Iran. Iran bought the jets in the 1970s before the American government banned most exports, including defense-related sales, to the Middle East country.

“There is no way that Iran should be getting these sensitive military parts, especially with the situation in the Mideast so turbulent,” Mr. Kerry said.

Federal investigators say that in at least one instance, gear purchased from Pentagon surplus got to Iran. A Pakistani arms broker bought Chinook helicopter engine parts for Iran from an American company that had bought them in a Pentagon surplus sale, and those parts made it to Iran, according to Immigration and Customs Enforcement agents. They spoke on condition of anonymity because of the sensitivity of the issue.

Sensitive surplus is supposed to be rendered useless for military purposes or, if sold, then only to buyers who promise to obey American arms embargoes and other laws. Defense Department official Fred Baillie said the Pentagon did nothing wrong in selling the surplus.