The three-pronged measure being considered by Canadian Health Minister Ujjal Dosanjh would prevent Canadian doctors from countersigning prescriptions for U.S. patients without examining them in person, spokesman Ken Polk said.

It also would prohibit prescriptions for foreigners who are not present in Canada and create a list banning certain drugs that are widely used by Canadians from being exported, Polk said.

A proposal was expected to be presented to Prime Minister Paul Martin's cabinet by the end of the month, Polk said, although Asian tsunami aid efforts were diverting government resources and it was not clear how much time would be required for approval.

"He's made it pretty clear that he wants that unethical practice to stop," Polk said of Dosanjh.

New legislation, but not changes to existing regulations, would require support from opposition parties as well as Martin's minority government to pass. It was not clear whether a ban on co-signing prescriptions could be accomplished by just changing regulations.

The issue has become politically touchy for President Bush, whose administration has argued that reimporting U.S.-made drugs from Canada would put consumers at risk because U.S. regulators could not guarantee their safety. The pharmaceutical industry, which donated heavily to Bush's re-election campaign, vehemently opposes reimporting drugs, which undercuts their U.S. sales.

But importing cheaper drugs from Canada is popular with lawmakers of both parties and has considerable support in Congress. The House already has passed a bill allowing reimportation once, and lawmakers in both parties say it would pass the Senate if Republican leaders would allow it to come up for vote there.

If legislation allowing reimportation were approved by Congress, Bush could face a difficult decision as to whether to sign the bill.

While reimporting drugs is technically illegal, those laws are not enforced. Ten million illegal shipments of prescription drugs worth $1.4 billion entered the United States in 2003, about half of them from Canada.

The issue is particularly sensitive for lawmakers representing northern U.S. states, where consumers sometimes travel to Canada to purchase cheaper drugs. Republican Gov. Tim Pawlenty of Minnesota has set up a Web site to help Minnesotans buy cheaper drugs from Canadian pharmacies, similar to I-SaveRx.com, a site helping people do the same in four other states.

Representatives of both the U.S. and Canadian governments say President Bush discussed the issue with Martin when he visited last fall. That has sparked accusations that Bush pressured Martin to change Canadian policy -- an accusation that the White House denies.

Existing Canadian law says Canadian doctors must "attend upon" a patient when co-signing a prescription. "We may need to make that language more explicit," Polk said.

Louise Crandall, spokeswoman for the Canadian Pharmacists Association, said the cross border trade is responsible for rising drug costs in Canada, that it was unethical for doctors to co-sign prescriptions without examining patients and that the estimated 42 million Americans who are un- or underinsured would drain Canada's drug supply.

David MacKay, executive director of the Canadian International Pharmacy Association, whose 35 member pharmacies mostly in western Canada control up to 85 percent of the cross border business, said the solution to fears that the United States will drain Canada's drug supply is to ban wholesale purchases.

"The fear . . . is bulk distribution, the Cost-Cos the Wal-Marts and the Safeways dumping huge quantities into the U.S. That would jeopardize the Canadian drug supply, but that's not what we do," MacKay said.