Prime Minister Stephen Harper has announced a new round of sanctions in response to what he calls the "escalated acts of aggression" by Russian-backed fighters in eastern Ukraine.

Harper's office issued travel bans Tuesday against 37 Russian and Ukrainian individuals and economic sanctions against 17 Russian and Ukrainian entities.

The Canadian government to date has made about a dozen such announcements since the Russian military began to intervene in the conflict in February 2014.

Harper singled out "the indiscriminate attacks in and around the Ukrainian city of Mariupol on Jan. 24," as one reason to step up sanctions.

"Canada's position remains clear: we recognize the sovereignty and territorial integrity of Ukraine and will never recognize the illegal Russian occupation of any part of the country," Harper said in a statement.

"In co-ordination with our EU and U.S. partners, Canada is once again intensifying its response to the situation by announcing further sanctions against Russian and Ukrainian individuals and entities," he said.

Harper said his government is closely monitoring the implementation of the ceasefire agreement reached by Russian and Ukrainian leaders in Minsk on Feb. 12 and added he is prepared to take further action against Moscow and Russian-backed rebels if they fail to adhere to the pact.

The truce in eastern Ukraine was supposed to take effect on the weekend, but the fighting has not let up. Fighting has been particularly heavy in recent weeks in and around Debaltseve, a strategic Ukrainian town now surrounded by rebel forces.

The conflict has already killed more than 5,600 people and displaced more than a million, the United Nations said on Monday.