Opposition MPs continued their attack on Health Minister Allan Rock in the House of Commons Thursday over an alleged conflict of interest in the government's purchase of the anti-anthrax antibiotic Cipro.

Opposition members allege that Rock was in a conflict of interest when his department ordered Cipro pills from Toronto-based pharmaceutical company Apotex, because Rock used to represent the company when he was a private lawyer.

During Question Period Thursday, Rock fended off attack after attack as MPs tried to punch a hole in Rock's assertion he had nothing to do with a $1.5-million contract awarded to Apotex Inc.

Tory MP Andre Bachand lashed out at Rock for comments Rock made earlier in the day at a Commons health committee. Bachand had asked whether the prime minister knew that Rock used to work for Apotex. Rock replied:

"This is outrageous if this man has something to allege against me let him do it, let him do it or shut up."

Bachand took issue with that kind of talk later in Question Period.

"This morning the minister of health told me to shut up. I will not shut up, okay?" an angry Bachand said. "The evidence is mounting. It's clear now that the minister of health in the past had close relations with Apotex."

Rock replied: "I wish the member would take my advice," and challenged Bachand to make such an allegation outside the House of Commons, where MPs do not enjoy parliamentary privilege against slander or libel.

Rock did, however, concede that he did legal work for Apotex and other brand name drug companies in the mid-1980s "from time to time."

During the earlier committee hearing, Alliance health critic Diane Ablonczy grilled Rock about when exactly the government decided to buy the generic version of Cipro.

Ablonczy repeatedly asked Rock: who made the decision to order the generic drug and circumvent the patent laws?

Rock insisted it didn't matter how the government got the drugs. What matters, he told the committee, is that Health Canada secured the pills quickly to ensure the health of Canadians.

"Today we have the security of access to antibiotics we did not have a week ago, and that Madame Chair, is what's important in protecting Canadians' security," said Rock.

Apotex tried to come to the minister's defence Thursday. A spokesperson says Rock did act as a lawyer for them almost 20 years ago, but it was the law firm they retained -- not him personally. Any suggestion of favourtism, they say, is absurd.

Working on smallpox vaccine

In between questions about Apotex, Rock also told the committee that Health Canada is mulling over whether to stockpile 30 million doses of smallpox vaccine.

Rock told the Commons health committee that a terrorist attack using smallpox would be far more dangerous than one using anthrax. That's because the smallpox virus is highly contagious.

While the virus was eradicated back in 1970s, samples are kept in labs around the world and could be used by terrorists to start an infection.

Canada has only 380,000 doses of vaccine, left over from the 1970's. Rock says he thinks 30 million doses should be on hand.

Rock told the committee that smallpox vaccine is in very short supply in the world and those who have it don't have it for sale. He says the government has talked with U.S. authorities about a joint project to develop a new and improved vaccine.

``I don't believe we should go out and vaccinate 30 million people today,'' he told MPs. ``But we should have at least 30 million doses.''