WASHINGTON � The US Army has recalled 44,000 helmets that failed ballistic tests and federal authorities are investigating the firm that manufactured them, officers said on Monday.

The helmets, made by ArmorSource in Hebron, Ohio, were issued to American troops since 2007, including an unknown number of soldiers in Iraq and Afghanistan, Brigadier General Pete Fuller told reporters.

"We don't know where they (helmets) are. So they could be on some soldier's head in either Iraq or Afghanistan. They could also be anywhere else in the world," Fuller said.

The move came amid a probe by the Justice Department, which launched an investigation in January into ArmorSource's helmet contract, and after a recent round of tests raised concerns, Fuller said.

The helmets were subjected to "worst case scenarios" at a Maryland shooting range and while they failed to meet the army's standards, the test results gave no indication soldiers would be at risk of lethal injury, officers said.

"In ballistic tests, the helmets fell short of the Army standards, not by much, but the standards are absolute. And if you don't meet them, you don't meet them," said Colonel William Cole.

The test results on the helmet came a day after the Justice Department officials provided "critical additional details" about their investigation, prompting the Pentagon to launch the recall, Fuller said.

Officials declined to offer details of the Justice Department investigation.

The military had an ample supply of the same helmets made by three other contractors that would allow troops to exchange the recalled helmets manufactured by ArmorSource, officers said.

Some soldiers in Afghanistan had already exchanged their helmets after commanders were notified last Thursday.

"We're doing due diligence... (because) a vendor under investigation might not have done all they should have done, we wanted to ensure there's no risk ever put to our soldiers," Fuller said.

"So we're recalling all the helmets associated with that vendor."

The army first had concerns about the contractor's work last year as paint on the helmet was peeling off, said Fuller, who oversees equipping army troops.

The Advanced Combat Helmet is standard issue for all Army troops and is also used by the Air Force, Navy and Coast Guard. The Marine Corps use a slightly lighter version that has also been recalled, but those helmets had not been distributed yet, officers said.

The 44,000 recalled helmets -- which cost 250 dollars each -- represent about four percent of the total number of Advanced Combat Helmets in the military's inventory, Fuller said.

Under an August 2006 contract, ArmorSource manufactured 102,000 helmets. Of that number, 44,000 were distributed to troops and have been recalled, while 55,000 are still in storage and the military refused to accept the remaining 3,000, Fuller said.

As a result of the tests and ongoing investigation, all the helmets made by ArmorSource in the military's inventory will be destroyed, he said.