Canada will draw up legislation giving it the right to ban the bulk sale of prescription drugs and other medicines to the United States when necessary to ensure sufficient supplies in Canada, Health Minister Ujjal Dosanjh said on Wednesday.

Dosanjh said the government must be able to block plans by some U.S. states to make bulk purchases of medicines from Canada, where prices are generally lower because of government-imposed limits on what pharmaceutical companies can charge for their drugs.

He also said Ottawa would stop the current practice of Canadian Internet pharmacies selling cheap medicines to Americans who do not have an established relationship with a doctor in Canada.

“In light of potential American legislation legalizing the bulk import of Canadian prescription and other medications, our priority must be the health and safety of all Canadians and the strength of our health care system,” said Dosanjh.

“We must be proactive in making sure that the supply of affordable prescription medications remains stable and sufficient to meet the needs of Canadians.”

Pharmaceutical companies have threatened to halt shipments to Canada if the drugs are transported back to the United States and sold at levels that undercut U.S. prices.