WASHINGTON (CNN) -- A safety alert was issued on Thursday to U.S. military commanders in Afghanistan after investigators found that a contractor allegedly failed to properly carry out a job aimed at reducing the threat of roadside bombs.
The alert that warned troops of possibly heightened danger was issued by the Special Inspector General for Afghanistan Reconstruction, which oversees spending for that war.
"The fact that we issued an alert in the midst of an ongoing investigation speaks to its urgency," an investigative official, who did not wish to speak publicly, told CNN.
The official, who called the warning "a matter of life and death," said the watchdog agency was tipped to the matter in August by a U.S. service member in Afghanistan.
"They alerted us to the fact that the work was not fixed," the official said.
Phil LaVelle, a spokesman for the special inspector general's office, said the contractor would not be identified while the investigation was ongoing.
The Afghan contractor received more than $360,000 in February for work aimed at combating improvised explosive devices, which kill more U.S. troops than any other single weapon.
The contractor was to install about 125 "culvert denial systems" along a major highway. The plan was to place metal screens under roads so militants could not access storm drains and plant bombs.
But in the safety alert to top military commanders, the special inspector general's office warned that investigators had "identified significant contract fraud" in the installation and inspection of the culvert systems.
The warning added that Afghan contractors reported the job as complete when, in fact, a large number of metal grates were improperly installed or not put in place at all.
The military told Congress this month that improvised explosives are becoming more prevalent in Afghanistan.
Insurgents planted 16,000 last year and that figure is likely to exceed that in 2012. The Pentagon has spent more than $50 billion to combat the threat, even establishing a command dedicated to this one problem.