WASHINGTON (AP) – Narcotics are easily bought without a prescription from online U.S. pharmacies, say congressional investigators who sometimes found stricter standards from Internet outlets in Canada.

“It seems that the key thing here is having your credit card,” Robert Cramer, a senior investigator with the General Accounting Office, said Thursday at a Senate Governmental Affairs subcommittee hearing on the risks of buying medications online.

Agency employees who posed as patients purchased the painkiller hydrocodone – the generic version of Vicodin – from eight Web sites in the United States. The employees were not required first to see a doctor or provide a prescription, Cramer said.

In addition, they paid three to 16 times what the painkiller costs at local pharmacies, suggesting that the Internet drug operations are catering to people who cannot get medications conventionally.

Investigators found widespread problems purchasing prescription medicines from many foreign countries. Some drugs were counterfeit; many arrived without instructions or patient warnings.

Opponents of legalizing prescription drug imports cite the potential danger from drugs purchased on the Internet as a reason for their opposition. The Food and Drug Administration says it cannot guarantee the safety of the foreign products.

Former New York Mayor Rudolph Giuliani said his research, funded by the pharmaceutical industry, shows that U.S. government inspectors look at only about 10 percent of packages containing pharmaceuticals that are sent from abroad. “It is pretty much right now a wide open system,” Giuliani told senators.

Yet congressional investigators said they ran into few problems with medicines purchased from Canadian Web sites.

All 18 Canadian sites required consumers to supply a physician-written prescription before filling orders. That was the case for five of 29 U.S. pharmacies; no other foreign pharmacies did.

Sen. Carl Levin, D-Mich., who advocates drug imports from Canada and elsewhere, said the GAO’s work led him to conclude “medicines purchased from Canada are as safe or safer than those purchased in the United States.”

Several bills would strengthen federal regulation of domestic Internet pharmacies and inspections of pharmaceutical manufacturing plants abroad.