NEW YORK (CNN/Money) - The photograph shows two identical pills, side by side. "Quick," reads the caption. "Pick the capsule that hasn't been tampered with."

The viewer, of course, can't tell. And that uncertainty is what the ad from the group that speaks for the pharmaceutical industry wants to convey about the risks of Americans buying cheaper prescription drugs in Canada.

By crossing the border and now online, Americans, many of them elderly, have been buying drugs through Canadian pharmacies for years. But that may become more difficult.

Regulators have mostly ignored rules prohibiting the purchase and import of prescription drugs when the same treatment is available at home. Now, the Food and Drug Administration appears to be abandoning a relaxed view toward drugs sold to Americans by pharmacies in Canada, where government price-caps keep a lid on costs.

"We are outraged," said Joel Barkin, a spokesman for Rep. Bernard Sanders, I-Vt., who has led bus trips to Canada to buy cheaper drugs.

Bob Whitelaw, president of the Canadian Council of Better Business Bureaus, said the FDA has sent letters to Canada's pharmacies asking them to halt sales to the U.S.

The New York Times and the Wall Street Journal reported this week that William K. Hubbard, the FDA associate commissioner for policy, is taking a tougher stance on prescription drug imports.

Related Stories Merck's Medco got $3B in rebates Pfizer in talks to settle drug probe FDA to require bar codes on drugs

All parties "who cause a prohibited act" can "be found civilly and criminally liable" under the federal Food, Drug and Cosmetic Act, Hubbard wrote in a Feb. 12 letter, according to the Journal.

"Virtually all shipments of prescription drugs imported from a Canadian pharmacy will run afoul" of federal law, the Times quoted Hubbard as saying.

The FDA did not return a call requesting comment, though the agency is reportedly not focused on senior citizens who buy drugs and is more concerned about pharmacies and insurers that enable drug imports.

Outfits like Crossborderpharmacy.com and Canadianpharmacygroup.com proliferate on the Internet, promising to fill prescriptions online. A spokesman for one of them, Canadianpharmacylink.com, said its "primary" business is selling drugs to Americans.

"These are elderly people and the savings really means a lot to them," said Satish Kumar, a spokesman for the company. "They are very happy and relieved that they can save money."

He criticized the U.S. pharmaceutical industry's characterization of Canadian drugs as unsafe. "Some of our standards are higher than the U.S," Kumar said.

A statement from the Pharmaceutical Research and Manufacturers of America, which designed the ad described earlier, insists that buying drugs abroad carries risks not found at home.

"Federal law on prescription drug imports and reimports reflects well-documented concerns about the safety of imported drugs, and the probability that many such drugs will be unapproved, adulterated, contaminated or counterfeit," the group said.

That position is backed up by the AARP, where a spokesman, Marty Davis, said "there are health and safety issues concerned with purchasing drugs outside the U.S."

FDA Commissioner Mark McClellan, speaking at the National Consumers League Consumer Health Forum, in February, made similar comments.

"The drugs that are purchased from Canada are not subject to any clear regulatory oversight, so nobody is doing what the FDA does for U.S. drugs, which is take clear steps to try to make sure that those products are safe and effective, or accurately labeled, not misbranded, not adulterated," McClellan said.

But the spokesman for Rep. Sanders contends that the industry simply feels threatened by losing business to Canada.

"We pay more for prescription drugs than any other country in the industrialized world," said spokesman Joel Barkin, who released figures contending that drugs like Flonase, for allergies, and Avandia, for diabetes, can be bought for about half the price through a Canadian online pharmacy.

Barkin accused the Bush administration of bowing to lobbying from U.S. drugmakers.

The most vocal drug company to enter the debate has been GlaxoSmithKline (GSK: Research, Estimates), the U.K.-based drugmaker. Glaxo in January said it will not supply prescription drugs to Canadian wholesalers and pharmacies that export medicines outside Canada.

"Instead of being encouraged to support illegal trade and poorly regulated and potentially unsafe business practices, American seniors should be encouraged to contact their congressional representatives to pass a Medicare prescription drug benefit," Glaxo said.

Proposals to provide the elderly with relief from rising prescription costs will likely be taken up this year in Congress. But with the budget deficit rising, he costs of such benefits have already generated debate.