WASHINGTON — The Army made critical mistakes in tests of a new body armor design, according to congressional investigators, who recommend an independent review before the gear is issued to troops in Iraq and Afghanistan.

The Government Accountability Office report says the Army strayed from established testing standards and that several of the designs it passed would have failed had the tests been done properly.

The Army has ordered about 240,000 of the new type of bullet-blocking plate to be used in ballistic vests, but doesn't plan to rush the armor into combat. The plates will be stored to meet future demands, according to service officials.

In a lengthy response to the GAO report, Defense Department officials reject the call for an outside look. They acknowledge that a few problems occurred during testing. But these were minor miscues, they said, that don't shake their confidence in the overall results.

Given the military's opposition to an external review by ballistics experts, Congress should decide whether such a step is necessary, the GAO says.

In a letter sent yesterday, Reps. Neil Abercrombie, D-Hawai'i, and Roscoe Bartlett, R-Md., urged Army Secretary John McHugh to follow the GAO's recommendations. They did not, however, say what they would do if McHugh doesn't.

Abercrombie is chairman of the House Armed Services air and land forces subcommittee; Bartlett is the panel's top Republican.

The GAO report is the latest study to call into question the Army's ability to oversee the production of a key piece of battlefield equipment.

In January, the Pentagon's inspector general faulted the Army for not properly overseeing a series of tests on an earlier model of the protective plates at a private ballistics laboratory.

The inspector general's audit recommended that nearly 33,000 plates be pulled from the Army's inventory of nearly 2 million because the inserts might not provide troops with adequate protection. The Army disputed the findings, but withdrew the plates as a precaution.

Stung by the inspector general's conclusions, Army officials dismissed the private laboratories they'd long relied on for the tests and said they would do the vital job themselves at a military facility in Aberdeen, Md.

That proved to be a contentious decision, however. The testing companies and manufacturers of the plates insisted that the private sector could do the trials better, faster and for much less money.

With the GAO report, that argument gets new traction.

In their letter to McHugh, Abercrombie and Bartlett said the move may have been "premature." They want him to review why the Army would exclude the independent, private laboratories, which are certified by the National Institute of Justice.