Canada is deploying a warship to help reassure NATO allies anxious over the crisis in Ukraine as Ottawa deepens this country's military commitment to standing up to Russian aggression in Europe.

Three members of the Canadian Armed Forces have also taken the helm of an international military observation team in Ukraine tasked with investigating the eroding security situation there.

Canada's investment in the Ukraine crisis now includes the frigate HMCS Regina, six CF-18 fighter jets, one heavy lift plane, two Airbus transports and an estimated 250 military personnel in Romania – a deployment that's taken place without consulting Parliament.

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The news came as Ukraine's acting President conceded that his police and security forces could do little to control the growing unrest in the country's east, where pro-Russia militants took control of more government buildings on Wednesday. The West believes Moscow is behind this.

The three Canadians head a small Organization for Security and Co-operation in Europe (OSCE) team tasked with arms inspections in designated regions of Ukraine – but not Crimea, which has been annexed by Russia. The mission's goal is to dispel concerns about "unusual military activities" in Ukraine and ensure a continuous international military presence, the Department of National Defence said.

Last week, members of another OSCE team were detained by pro-Russian militants in Eastern Ukraine. Eight observers were held on allegations they were spying for NATO. One Swedish officer was released Sunday.

Acting Ukraine President Oleksandr Turchynov has launched "anti-terrorist" operations to regain control of Ukraine's east, but to little effect. A dozen cities are now controlled by the insurgents.

Yulia Tymoshenko, a former prime minister and presidential candidate, is urging Ukrainians to join a resistance force that could act in co-ordination with the army. Ukraine will hold its presidential election on May 25.

The HMCS Regina is currently deployed in the Arabian Sea and will join the North Atlantic Treaty Organization's Standing Maritime Forces "as part of NATO's reassurance package," the Canadian government said Wednesday.

"Russia's illegal occupation of Ukraine and provocative military activity remains a serious concern to the international community," Prime Minister Stephen Harper said. "Canada remains committed to working with our NATO allies to promote the sovereignty and territorial integrity of Ukraine."

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On Tuesday, Ottawa bade farewell to six CF-18 Hornets that are being assigned to conduct air policing and training exercises in Central and Eastern Europe as NATO beefs up patrols of member states neighbouring Russia.

The Conservative government would not say whether the HMCS Regina's ultimate destination is the Black Sea south of Ukraine and Russia.

"Planning is currently under way and we are awaiting direction from NATO and our allies on how the HMCS Regina will be employed," said Johanna Quinney, press secretary for National Defence Minister Rob Nicholson.

Canada's military contributions come without a vote or a formal debate in the House of Commons, raising questions about how much deliberation should occur among MPs before such a deployment.

University of Ottawa professor Philippe Lagassé, an expert on Canada's national defence policies, said he was surprised opposition MPs did not push for a take-note debate on the matter. While such a debate would not be binding on the government, it could help establish the parameters of Canada's role and the government's objectives for the mission, he said.

"I'm a little baffled by the fact that this is occurring and the opposition seems to have no real inclination to debate the issue," Prof. Lagassé said.

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With a report from the Associated Press