Health Canada has fired three scientists who criticized the department's drug approval policies.

Shiv Chopra, Margaret Haydon and Gerard Lambert received letters of termination on Wednesday, said Steve Hindle, president of the Professional Institute of the Public Service.

Health Canada spokesperson Ryan Baker denied the three were fired because of anything they said publicly. He says the reasons are confidential and are included in the letters of termination.

The three have been involved in a series of high-profile clashes with Health Canada.

They criticized Monsanto's bovine growth hormone, which led to a Senate inquiry and a decision not to approve the drug. They also questioned carbadox, a drug used in pigs, and Baytril, which was used to promote growth in cows and chickens.

Haydon called a 2001 Canadian ban on Brazilian beef a political decision, and Chopra criticized former health minister Allan Rock for stockpiling antibiotics during the post-Sept. 11 anthrax scare.

Prior to the May 2003 discovery of mad cow in Canada, both Hayton and Chopra also warned measures to prevent the disease were inadequate. They had called for a ban on the use of animal parts in feed.

The association representing the scientists plans to mount a legal challenge to have the scientists rehired.