OTTAWA -- Prime Minister Stephen Harper and other leaders expressed grave concerns Saturday over Russia’s approval of military intervention in Ukraine.

Harper spoke with U.S. President Barack Obama to co-ordinate international efforts to de-escalate rising tensions and fears in the region after Ukrainian officials signaled they would repel a Russian invasion with force. Obama also spoke with French President Francois Hollande.

All agreed Ukraine’s sovereignty and territorial integrity must be respected under international law, the White House said in a release.

They also pledged to work together on a package of support and aid to help Ukraine as it pursues reforms and stabilizes its economy, American officials said.

In a statement Saturday evening, Harper condemned Putin’s military intervention.

“These actions are a clear violation of Ukraine’s sovereignty and territorial integrity. They are also in violation of Russia’s obligations under international law,” Harper said, adding Canada recognizes the “legitimacy of the Government of Ukraine.”

Canada has suspended its engagement in preparations for the G-8 Summit, currently planned for Sochi, and the Canadian ambassador in Moscow is being recalled for consultations.

“Canada supports the immediate deployment of international monitors from the United Nations and the Organization for Security and Cooperation in Europe (OSCE) to Ukraine. We are also engaged in discussions aimed at developing a financial aid package for Ukraine,” Harper said.

“Ukraine’s sovereign territory must be respected and the Ukrainian people must be free to determine their own future. We call on President Putin to immediately withdraw his forces to their bases and refrain from further provocative and dangerous actions.”

He also warned if Putin continues with an invasion, “it will lead to ongoing negative consequences for our bilateral relationship.”

Harper was on the phone with his counterparts in England and Germany before the weekend to begin the process for a united front and to find a political solution.

The prime minister also gathered key members of his cabinet Saturday for an emergency meeting after Russia’s parliament approved troop deployment to the region.

Meanwhile, Canadians were encouraged to leave Crimea or stay indoors because of escalating military activity, political unrest and ongoing demonstrations and clashes.

Foreign Affairs issued a travel advisory, saying Canadians should also avoid travel to the region.

“If you are presently in Crimea, you should consider leaving while it is safe to do so. If you are unable to exit the country safely, remain indoors,” the advisory says.

The government’s concerns follow the seizure of the Crimean Parliament and two airports in the area last week by armed groups.

“The security situation is currently unpredictable and may deteriorate further with little or no warning,” Foreign Affairs said.