Federal agents arrested dozens of current and former Boeing workers on Thursday on charges of illegally dealing in painkillers and anti-anxiety drugs at a plant that makes military aircraft models used in the Iraq and Afghanistan wars.

Workers were led in handcuffs out of the Ridley Park, Pennsylvania, plant in the early-morning bust by agents wearing FBI and DEA bullet-proof vests, witnesses said.

As a result of an investigation that began four years ago at the Boeing plant, 23 people were charged with selling the prescription painkiller Oxycontin and other drugs, U.S. Attorney Zane David Memeger told a news conference in Philadelphia.

Another 14 people were charged with attempted possession of various drugs for trying to buy them, he said.

Boeing employs more than 6,000 people at the Ridley Park plant, where the V-22 Osprey vertical take-off aircraft and H-47 Chinook helicopters are produced. The Osprey and Chinook are standard U.S. military aircraft used in Iraq and Afghanistan.

There was no evidence that the integrity of the work on any aircraft had been compromised, Memeger said.

This investigation and prosecution focused not only on the sellers, but also on the users because of the critical role that these employees play in manufacturing military aircraft, Memeger said.

Vito Guarino, acting Drug Enforcement Administration special agent in charge, said: These sales placed the individual abusers as well as society at large at risk.

Boeing spokesman Damien Mills said Boeing cooperated with the investigation and took steps to make sure the employees under suspicion were in no position to compromise the safety or quality of the aircraft.

All but one of those charged is a current or former Boeing employee, authorities said. Another person was expected to be arrested as well. The employees charged in the case were suspended, Boeing said.

SHOCKED

A Boeing sheet metal assembler drinking a beer at the nearby Burgundy Lounge after his shift ended on Thursday said he had been aware of some illegal drug activity but did not know how widespread it may have been.

It's kind of like high school, said the 20-year Boeing veteran who did not want to be identified. If you are looking for something, you know where to go to look for the stuff.

He added that he had never seen another worker obviously under the influence of drugs at the plant, located in an industrial suburb west of the Philadelphia International Airport.

Another Boeing sheet metal worker, who also did not want his name used, said his co-workers had been shocked to see fellow employees led out of the plant in handcuffs.

He said many people he knew were unaware of any drug use at the plant.

But he said: These things can happen in any plant in the country. It probably has a lot to do with stress.

During the investigation, agents found evidence of the powerful painkiller Oxycontin as well as fentanyl, which is sold in lozenge form as Actiq, being dealt at the plant, officials said.

Also found were the painkiller buprenorphine, which is sold as Suboxone, and the anti-anxiety drug alprazolam, sold as Xanax, they said.

The investigation was triggered in 2006, Mills said, when some employees contacted the company's internal ethics hotline with suspicions that there was illegal drug activity at the plant.

He said Boeing launched an internal probe and in August 2007 turned its findings over to federal investigators.

Boeing issued a statement saying it commends the U.S. Attorney's Office, and other federal law enforcement agencies for their rigorous and thorough investigation, throughout which we took appropriate steps to ensure safety of our employees and the absolute integrity and quality of the products we produce for our customers.

If convicted, those charged with distribution face possible sentences of 10 to 260 years in prison and millions of dollars in fines, the U.S. Attorney's office said.