WASHINGTON — The Government Accountability Office has rejected a claim that testing of improved body armor for U.S. forces was flawed, clearing the way for the Army to get the stalled $1 billion project moving again.

Had the GAO agreed with a contract protest filed in July by ArmorWorks of Chandler, Ariz., the program to buy sturdier armor could have been delayed for months. That would have been bad news for the Army, which has been criticized for moving too slowly to provide troops in Iraq and Afghanistan with the best battlefield gear.

ArmorWorks accused the Army of not following accepted testing standards after the company's protective plates failed when armor-piercing rounds were fired at them.

Once a protest is filed with the GAO, work on a contract is put on hold until the complaint is resolved.

Three other companies passed the tests that took place at Aberdeen Proving Ground in Maryland between February and June. That means they'll compete for as many as 1.2 million sets of body armor the military will buy over the next five years.

A copy of GAO's ruling on the ArmorWorks protest has not been made public. The GAO's Web site states only that the case was dismissed on Tuesday.

The body armor used by American forces in Iraq and Afghanistan consists of a vest with specially hardened ceramic plates that deflect enemy ammunition. The plates, called ESAPI, have proved to be lifesaving equipment.

ArmorWorks has been one of the military's major supplier of ESAPI plates.

Concerned that new and more potent bullets will soon find their way onto the battlefield, the Army more than a year ago opened the bidding for even sturdier plates called XSAPI.

The three companies that passed the Army's XSAPI testing — Ceradyne of Costa Mesa, Calif., BAE Systems of Phoenix, and The Protective Group of Miami Lakes, Fla. — are now expected to receive contracts for the improved plates. Additional testing is required before the armor is bought in bulk and used by the troops, however.