Canada is flatly rejecting Donald Trump's suggestion to reinstate Russia in the G7, four years after it was expelled from the group of industrialized nations for annexing Ukraine's Crimea.

Before departing for the G7 summit in Charlevoix, Que., the U.S. president called on the G7 leaders to let Russia back in.

"It may not be politically correct, but we have a world to run. And in the G7, which used to be the G8, they threw Russia out. They should let Russia come back in. Because we should have Russia at the negotiating table," he told reporters.

But Canada, which pushed for Russia to get the boot in 2014, is not onside.

Foreign Affairs Minister Chrystia Freeland said Canada's position has not changed.

"Russia was invited to be part of this club and I think that was a very wise initiation, and an invitation full of goodwill," she told reporters at the summit.

"Russia, however, made clear that it had no interest in behaving according to the rules of Western democracies."

Former prime minister Stephen Harper said Russia should never be allowed back in the G7 as long as Vladimir Putin is in power.

"Canada would very, very strongly oppose Putin ever sitting around that table again. It would require consensus to bring Russia back and that consensus will just not happen," he said in 2015.

"Russia is more often than not trying deliberately to be a strategic rival, to deliberately counter the good things we're trying to achieve in the world for no other reason than to just counter them."

In April, the Liberal government expelled four Russian diplomats, declaring them unwelcome in the country amid allegations about Moscow's role in the poisoning of a former spy and his daughter.

US President Donald Trump is traveling to the G7 meeting in Charlevoix 0:57

Russia's Foreign Ministry responded by expelling an equal number of Canadian diplomats along with representatives of other countries, including Australia, France and Finland.

Russia became a full member of what became known as the G8 in 1997 and hosted the 2006 summit in St. Petersburg.

Italy agrees with Trump

The group suspended Russia's membership after its annexation of Crimea. A meeting that Russia was set to chair in Sochi was moved to Brussels. Since then, the group has been known as the G7 again.

Italian Prime Minister Giuseppe Conte agreed with Trump that Russia should be readmitted, saying it is "in everyone's interest."

European Council President Donald Tusk said Russia is less interested in the G7 format than other members. He prefers to keep the group to seven, quipping that it is a "lucky number."

According to the Russian government-controlled news agency Sputnik, Kremlin spokesman Dmitriy Peskov responded to Trump's statement by saying, "Russia is focused on other formats, apart from the G7."

Peter MacKay, former minister of foreign affairs, joins Power & Politics to discuss the state of affairs as G7 leaders meet in Quebec. 8:26

Russia experts in Canada say there are more disadvantages than advantages to letting Russia rejoin the group.

Piotr Dutkiewicz, a professor and Russian foreign relations expert at Carleton University, said no global issue can be effectively discussed today without China and Russia at the table, and it's better to have a stable, open channel of communication than to deal with the unknown.

But swallowing principle and allowing Russia back in would validate Putin's bad behaviour and harm the reputation of the G7 leaders, he said.

No redemption, no reinstatement

Aurel Braun, a professor of international relations at the University of Toronto's Munk School of Global Affairs, said Russia was expelled for very good reasons and has done nothing since to redeem itself.

"It's very hard to see how, just for the sake of having dialogue, one can develop a kind of amnesia about all of the other actions that Russia has taken, including domestic actions against dissidents and external aggressiveness, and no indication that this is about to change," he said.

Braun said that Trump likely raised the Russia issue to throw the discussions off balance and distract from the topic of tariffs. It also suggests Trump is taking the G7 less and less seriously, he said.