Health Minister Ujjal Dosanjh said Canada would ban the bulk export of prescription drugs when their supplies were low at home. But he left vague how the ban would be put into place - and whether it would affect the thousands of individual purchases that take place across the U.S.-Canada border and over the Internet.

The ban is an attempt to head-off an anticipated onslaught of drug demands from Americans if legislation pending in Congress legalizes Internet and bulk import of prescription drugs from Canada.

"Canada cannot be a drug store for the United States of America; 280 million people cannot expect us to supply drugs to them on a continuous, uncontrolled basis," Dosanjh said at a news conference.

Canadians must be assured access to an adequate supply of safe and affordable prescription drugs, Dosanjh said.

Individual sales would not necessarily be affected by the ban, but it could affect drug wholesalers or manufacturers in Canada. They are not permitted to export to the United States under U.S. law, but could do so under the legislation being considered in Congress.

He said he would introduce legislation when the House of Commons reconvenes this fall that would allow for the temporary ban of bulk exports when supplies are running low at home.

Americans pay the highest prescription drug prices in the world, and U.S. lawmakers are pushing to legalize the importation of wholesale prescription drugs as well as Internet purchases from Canada and other countries. Four bills are pending in Congress, but have met with opposition from the pharmaceutical lobby and from the Food and Drug Administration.

Some supporters of the Canadian exports said the proposed ban is a direct response to threats from the U.S. pharmaceutical industry.

"This is a big strong, wealthy industry and they're fighting as hard as they can fight so that they can charge the highest prices in the world for prescription drugs to U.S. consumers," said Sen. Byron Dorgan, D-N.D.

While it's legal in Canada for pharmacies to mail Americans drugs - after having been faxed or mailed their physician's prescriptions - it's illegal in the United States, though the laws are generally not enforced.

The Canadian government also maintains it is unethical for doctors to sign prescriptions without examining patients. Dosanjh said the definition of patient-physician relationship had to be clarified, but would not confirm whether that meant American patients would have to meet in person with Canadian doctors.

Any change in that definition, which Dosanjh said needed further study, could affect individual purchases.

"Our priority must be the health and safety of all Canadians and the strength of our health care system," Dosanjh said.

Carole Jaquez, a 79-year-old widow from Apple Valley, Calif., said she would support changes in U.S. law. She said the drugs she buys through a Vancouver doctor for her high blood pressure and asthma cost about $250 a month - half what they cost in the United States.

"I imagine we have to put the blame on the pharmaceuticals," she said in a telephone interview. "Why are they charging so much and why hasn't the administration in Washington done something?"

Anthony Wright, executive director of the Oakland, Calif.-based Health Access, a coalition of labor and consumer organizations, had another proposal. He said state and federal governments in the United States should imitate Canada and use their purchasing power to extract discounts from drug companies.

The Bush administration opposes prescription drug imports, and federal regulators warn they cannot guarantee the safety of drugs from outside U.S. borders. Canadian officials, however, have said Canada's regulatory regime is tougher than the U.S. one.

Dosanjh acknowledged no shortages currently exist, and the minister also conceded he was not aware of any injuries or illnesses to Americans purchasing drugs in Canada, where the government set prices typically 40 percent lower than those in the United States.

The drug-import program, I-SaveRx, uses a Canada-based clearinghouse to connect residents of Illinois, Vermont, Kansas, Missouri and Wisconsin to pharmacies and wholesalers in Canada, Ireland and the United Kingdom. Minnesota and Wisconsin also have state-operated Web sites to help residents import medications from Canada.