(Reuters) - At least 122 firearms from a botched U.S. undercover operation have been found at crime scenes in Mexico or intercepted en route to drug cartels there, according to a Republican congressional report being issued on Tuesday.
Mexican authorities found AK-47 assault rifles, powerful .50 caliber rifles and other weapons in late 2009 that were later linked to the U.S. sting operation to trace weapons going across the border to Mexico, the report said.
Guns from the program, dubbed "Operation Fast and Furious," also were found at the scene of the murder of a U.S. Border Patrol agent in the border state Arizona last December. It is not clear if they were the weapons responsible for his death.
The sting has become an embarrassment for the Obama administration and its Justice Department, rather than a victory in cracking down on the illegal flow of drugs and weapons to and from Mexico.
It has also hurt ties with Mexico, which has been battling the violent cartels in a war in which thousands have died.
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and federal prosecutors had hoped the sting would help them track gun buyers reselling weapons to cartels. But U.S. agents did not follow the guns after the initial purchaser re-sold them.
The House of Representatives Oversight Committee, led by Republican Darrell Issa, and the senior Republican on the Senate Judiciary Committee, Charles Grassley, have been investigating the sting and will issue the report Tuesday.
Their investigators say at least 122 firearms bought by suspected gun traffickers were found at Mexican crime scenes or caught going to the cartels.
Of the 2,000 weapons sold to the suspected gun traffickers, just over half remain unaccounted for, the report added. The Justice Department said that the ATF was not aware of the majority of those gun sales when they occurred.
"Given the vast amount of 'Operation Fast and Furious' weapons possibly still in the hands of cartel members, law enforcement officials should expect more seizures and recoveries at crime scenes," said the congressional report.
The independent watchdog at the Justice Department is also conducting its own investigation of the sting operation.
The Justice Department said it could only confirm 96 guns recovered in Mexico were tied to suspects being tracked in the operation, but it said that ATF did not have complete information on how many were recovered at crime scenes there.
The agency said another 274 weapons were recovered in the United States and, so far, about a dozen were found at U.S. crime scenes, according to information given to Grassley obtained by Reuters.
Soon after the sting began, Mexican authorities arrested a young woman with 41 AK-47s and a Beowulf .50 caliber rifle that were bought the previous day by a so-called straw buyer, or somebody buying a weapon for somebody else.
She told police she was taking them to the Sinaloa drug cartel, the congressional report said.
During a May, 2001 raid by Mexican federal police on the La Familia drug cartel, in which 11 members of the group were killed and 36 were captured, some of the more than 70 weapons recovered at the scene were traced back to the U.S. sting, according to the congressional report.
Issa's committee will hold a hearing later Tuesday with current and former ATF officials including those who worked in the U.S. embassy in Mexico who complained that they were kept largely out of the loop about the scope of the operation.
(Editing by Paul Simao)