WASHINGTON  The American military has not properly tracked tens of thousands of weapons the Pentagon bought and shipped to Afghan security forces, leaving the arms at risk of being stolen or sold to militants, according to a federal report that is to be presented at a House panel hearing on Thursday.

American military officials failed to keep complete records on about 87,000 rifles, pistols, mortars and other weapons  about one-third of all light arms the United States sent to Afghan soldiers and police officers from December 2004 to June 2008, auditors from the Government Accountability Office found. Further, American military trainers kept no reliable records on 135,000 more weapons donated by 21 countries, including Hungary, Egypt, Slovenia and Romania.

The report, which will be presented at a hearing of a House Oversight and Government Reform subcommittee, also found that Afghan security procedures were so inadequate that weapons supplied to Afghan forces were at “serious risk of theft or loss.” A copy of the report about the Afghan forces was provided to The New York Times by a Congressional official who sought to underscore the seriousness of the issue before the hearing.

“It’s critical that we not have weapons bleeding out of the system into the hands of insurgents,” said Representative John F. Tierney, a Massachusetts Democrat who leads the House committee’s national security and foreign affairs subcommittee.