Gregory Friedman, the department's inspector general, conducted the audit to see whether the department had eliminated backlogs in testing that were first detected in 2001.

"The audit disclosed that significant backlogs existed in each of the three types of tests conducted in the surveillance program -- laboratory tests, flight tests and component tests," he said in a report dated October 30.

Laboratory tests for seven of nine weapons systems in the testing program were behind schedule, and flight tests for six systems were behind scheduled.

"Furthermore, testing backlogs existed for all five primary weapons' components, such as gas transfer valves and detonators," he said.

Friedman noted that the role of the program to assure the reliability of warheads was increasingly important as the US stockpile of nuclear weapons ages.

"However, as a result of the continuing backlog of surveillance tests, the department lacks vital information about the reliability of the stockpile," he said.

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