LONDON, Ont. -- Canadian soldiers will take part in military exercises in Poland as part of NATO reassurance measures in response to the Ukraine crisis, Prime Minister Stephen Harper announced Friday.

"The (Vladimir) Putin regime's persistent military aggression and its ongoing illegal occupation of Crimea and other parts of Ukraine threaten the stability and security of central and eastern Europe," he said in London, Ont.

The NATO exercises will run in Swidwin, Poland from May 5 to 9 and will include about 50 soldiers from the 3rd Canadian Division based in Edmonton, comprised of a platoon from 3rd Battalion, Princess Patricia's Canadian Light Infantry and support staff. They were set to leave Friday, Harper's office said in a news release.

"They will conduct training in parachuting, airborne operations and infantry skills alongside Polish and American counterparts in this United States-led exercise with a view to enhancing Alliance interoperability and readiness," the prime minister's office said in the statement.

Canada has also diverted frigate HMCS Regina, which is currently on counter-terrorism and anti-piracy patrols in the Arabian Sea, to help NATO's efforts to send a message of resolve to Russia.

Harper did not say where the ship is headed, but NATO announced earlier this month it was beefing up maritime patrols in both the Baltic Sea and the Mediterranean.

Six Canadian CF-18 fighter jets left their base in Bagotville, Que., this week, headed for an air base in Romania, and eventual patrols along that country's border with Ukraine -- and possibly over the Black Sea.

Foreign Affairs Minister John Baird said Canada's actions are meant to send a "very loud, clear and tangible message" to Russia.

"Until Russia clearly demonstrates its respect for Ukraine's sovereignty and territorial integrity we will continue to work with our allies and our partners to further isolate Russia economically and politically," Baird said at a news conference in Ottawa.

There has been a "concerning" increase in the last day or two in violent actions in eastern Ukraine, Baird said, calling Putin a hypocrite for asking Ukraine to remove troops from parts of the country.

"Just imagine if a foreign power massed troops outside this department building, sent in thugs to start smashing the windows, then told us to withdraw our security guards," Baird said. "This kind of behaviour is completely unacceptable in the 21st century."

The federal government also said this week that a Canadian military officer is heading an international arms-control verification team investigating "unusual military activity" in Ukraine, but the inspections won't include the disputed Crimea region, which was annexed by Russia.

National Defence has also announced that a team of navy clearance divers would deploy next month for an exercise in Latvia, one of the Baltic states under threat.

Harper's announcement Friday came as U.S. President Barack Obama and German Chancellor Angela Merkel said in a joint news conference that further sanctions against Russia would be unavoidable if it disrupts a presidential election in Ukraine scheduled for May 25.

Both leaders made it clear that the next step would be to order sanctions on separate parts of the Russian economy or military -- on energy or arms for example -- but neither leader specified precisely what was being considered.

Pro-Russia forces shot down two Ukrainian helicopters Friday and Ukraine reported many rebels dead and wounded as the interim government in Kyiv launched its first major offensive against an insurgency that has seized government buildings across the east.