The federal government is sending as many as 40 military doctors, nurses and medics to Sierra Leone to help combat the Ebola epidemic, a deployment that comes after critics repeatedly asked Ottawa to dispatch much-needed medical workers to the region.

The Canadian Forces personnel will work at a 12-bed British military treatment centre for health-care workers in Kerry Town, south of the capital Freetown, beginning next month.

Health Minister Rona Ambrose, who announced the deployment alongside Defence Minister Rob Nicholson at an Ottawa hospital Thursday, placed the blame for the hold-up on the inability to guarantee that Canadians could be safely airlifted out of West Africa if they fell ill.

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"We didn't feel it was responsible for us to be encouraging people to go to West Africa until we felt very comfortable with the medical evacuation options for Canadians," Ms. Ambrose said. "We feel comfortable with that now."

Canada's failure to dispatch more personnel – above and beyond two rotating teams of laboratory scientists – to the outbreak zone sooner has not been the only knock against the Harper government's response to the Ebola crisis.

The federal Conservatives have also been castigated for their decision to stop processing visa applications from countries with widespread Ebola transmission, a move the World Health Organization has said is neither anchored in science nor in keeping with the International Health Regulations.

In his first public comments on the issue, Gregory Taylor, Canada's chief public health officer, defended the visa restrictions Thursday.

"It's striking that right balance, the right balance of protecting Canadians," he told The Globe and Mail after the announcement. "I think it's important to remember this is a virus we've never had in Canada before, we have no experience directly treating it and so far it kills half the people that it infects … so the visa [policy] is just one of those many measures to try and protect Canadians. I think it's very measured and it's very balanced."

When it comes to the evacuation question, Ms. Ambrose said Canada now has in place agreements with private air ambulance companies Phoenix Air – which has doubled its capacity – and Medic'Air.

Now that those arrangements are in place, Ottawa is partnering with the Red Cross in an effort to recruit more Canadian health-care staff to work at other treatment centres in Sierra Leone, Liberia and Guinea, the countries hardest hit by the Ebola outbreak.

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The vast majority of the 15,936 known cases of Ebola and 5,689 deaths from the disease have been reported in those three countries.

The Canadian Red Cross is hoping to deploy 160 medical personnel and support staff to the region soon.

Ottawa is also donating an additional $20.9-million to 10 humanitarian organizations aiding Ebola patients in West Africa, bringing Canada's monetary contribution to the fight to $113.5-million, the government says.

"I'm glad this is being done," Kirsty Duncan, the Liberal critic for international development, said of the deployment of the military personnel. "But the reality is for months our party has been calling on Canada to do what the World Health Organization has asked nations like ours to do, and that's contribute health-care workers to this unprecedented health-care crisis. Once again, it seems only shame can motivate this government."

Ms. Ambrose defended the time it took to answer the call for medical personnel, pointing out that Canada has been contributing in other ways, including donating its experimental Ebola vaccine and providing expert advice to the WHO.

"While some countries are sending many troops, Canada's real strength, a lot of our strength, is in expertise," she said. "If you think about the fact that we're the country that for 10 years has been researching Ebola and has come up with what is a very promising vaccine, we have some of the best and brightest on this issue."