Ukraine is asking Canada to apply more sanctions to Russia as fresh tensions between the Eastern European neighbours threaten to erupt into open conflict.

The country's ambassador made the appeal during an appearance before a Commons committee on Tuesday. He also asked that Canada extend its military training mission in his country and support its bid to join the NATO military alliance.

Ambassador Andriy Shevchenko also confirmed that Ukraine is close to buying high-powered sniper rifles from a Canadian company, but said Kyiv is still hoping the federal government will agree to provide weapons as aid.

Shevchenko's committee appearance, alongside counterparts from Georgia and Moldova, came weeks after Russian forces fired upon and seized three Ukrainian naval vessels and 24 sailors during a confrontation in the Black Sea.

The incident has been described as the worst round of direct violence between the two countries in years and followed Russia's support for elections in two breakaway regions of eastern Ukraine, votes condemned by Canada and others.

The three ambassadors were unsparing in their criticisms of Russian actions in eastern Europe, which they described as intentionally destabilizing, and warned that what happens there will have ramifications for the rest of the continent.

But while all three thanked Canada for its support over the years, Shevchenko also asked that Canada tighten its sanctions on Russia in retaliation for the naval confrontation and elections in Donetsk and Luhansk.

New U.S. and European sanctions had been imposed even before the two Ukrainian gunboats and a tugboat were seized near the Kerch Strait on Nov. 25. Shevchenko said he hopes the incident and the elections would prompt Canada to take action.

"Our view is that Canada is exploring new ways to put pressure on Russia. We also feel there is co-ordination between Canada and its western allies, and we welcome it," he told The Canadian Press after the committee meeting.

Joining the EU and NATO

Russia has accused Ukraine of instigating the incident in waters near the Crimean Peninsula, but Canada and other countries have sided with Ukraine in blaming Moscow.

The ambassador also confirmed talks are underway over renewing Canada's military training mission in Ukraine, which was established in 2015 and has seen Canadian troops train thousands of their Ukrainian counterparts.

The mission, involving 200 troops, is set to expire in March, but Shevchenko said his government is pushing for an extension and additional personnel as part of an expanded NATO presence in the country.

Shevchenko said his country is hoping Canada will lead the charge to admit Ukraine as a NATO member. Canada was one of the champions of such a move in the past, but that was before the Russian annexation of Crimea.

The entire alliance has taken a more cautious approach in recent years over fears that such a move could spark a major war with Russia, which has lashed out at what it sees as NATO encroachment.

Ukraine's parliament agreed last month to draft constitutional changes that President Petro Poroshenko says will compel future governments to seek to join the European Union and NATO.

Ukraine's sniper-rifle purchase was made possible when the Liberals added the country to the Automatic Firearms Country Control List. And while other arms deals are in the works, Shevchenko said Kyiv is still holding out hope, even after years of fruitless requests, that Ottawa will provide heavier weaponry to help Ukrainian forces better defend themselves.

"Many things have changed," Shevchenko said of Canada's rejection of past requests for lethal aid. "A lot of things have happened to make Canada much (more) concerned and serious about the Russian interference into Ukraine."