The federal health minister's office says it is keeping a close watch on the supply of three generic cancer drugs as doctors raise serious concerns about the risk of critical shortages across Canada.

The intravenous drugs in question are etoposide, vinorelbine and leucovorin.

Ginnette Petitpas Taylor's spokesperson Alexander Cohen says the government has facilitated the importation of an international supply of etoposide in the short term.

Cohen says companies are conserving existing supply for patients and the shortage for that particular drug is expected to be over by the end of September.

In the case of vinorelbine, he says the company Generic Medical Partners Inc. is putting in place a distribution plan to supply 75 per cent of demand for current orders by October and is also increasing production.

For leucovorin, Cohen says the federal government is working with companies on options to import an international supply as soon as possible.

"We're closely monitoring the supply of each of the three cancer drugs, and have taken specific measures to ensure Canadians continue to have access to them," he said in a statement.

CBC News reported on the weekend that hospitals in Ontario, Quebec, Nova Scotia and New Brunswick have been scrambling to find alternatives and make existing supplies of the drugs last as long as possible.