OTTAWA - After a week in which he twice weighed in on a high-stakes extradition case, John McCallum is out as Canada's ambassador to China - although for Conservative Leader Andrew Scheer, the damage has already been done.

“It should never have come to this,” Scheer tweeted Saturday, after the prime minister's office released a statement announcing McCallum's resignation at the request of Justin Trudeau.

That move came just hours after McCallum was quoted in a Vancouver newspaper saying it would be “great for Canada” if the United States dropped its extradition request for Meng Wanzhou, the Huawei executive who was detained in Vancouver last month.

McCallum told StarMetro Vancouver on Friday that if the U.S. and China reach an agreement on Meng's case, the deal should include the release of Michael Kovrig and Michael Spavor, two Canadians currently detained in China.

“We have to make sure that if the U.S. does such a deal, it also includes the release of our two people. And the U.S. is highly aware of that,” McCallum told the Star.

That comment followed a statement McCallum issued Thursday, saying he misspoke earlier in the week when he discussed Meng's case with a group of Chinese-language journalists in Toronto, listing several arguments he thought could help her with her legal fight against extradition.

McCallum's dismissal Saturday was too little too late for Scheer, who had called on Trudeau to fire the ambassador as early as Wednesday, on the grounds that McCallum's remarks raised concerns about the politicization of the Meng case.

“Justin Trudeau should have fired his ambassador the moment he interfered in this case. Instead, he did nothing and allowed more damage to be done. More weakness and more indecision from Trudeau on China,” Scheer tweeted Saturday.

In a brief scrum in Ottawa, Scheer accused the prime minister of damaging not only Canada's international reputation, but its chances of securing the release of Kovrig and Spavor.

He said McCallum's initial comments raised the spectre of political interference in the Meng case, and that by failing to act immediately, Trudeau undercut his own assurances that the case would be handled independently by the courts.

“This is, I think, part of a bigger problem. And that is Justin Trudeau's approach to diplomacy, where he thought he could conduct image-over-substance foreign affairs. And now Canadians are paying for his mistakes,” Scheer said.

“Canadians' treatment in China is being affected by this.”

Trudeau had initially come to McCallum's defence, after the first set of controversial remarks became public. The prime minister said earlier this week that his government's focus was on getting detained Kovrig and Spavor home safely from China and ensuring their rights are respected - and recalling McCallum wouldn't achieve that.

The PMO declined to comment on exactly what led to the prime minister's change of heart about McCallum's fate.

In a news release announcing the ambassador's resignation, Trudeau thanked McCallum for nearly two decades of service. He noted that McCallum served as minister of immigration and refugees between 2015 and 2017, during the height of Canada's effort to resettle Syrian refugees.

By appointing McCallum to the Beijing post in a cabinet shuffle in 2017, Trudeau picked someone who seemed well placed to push Canada's trade agenda with China even further.

McCallum had strong personal ties to China: his wife is of Chinese ethnicity and his three sons have Chinese spouses - something McCallum was fond of pointing out. He also had a large Chinese constituency in his former federal riding in Markham.

In the wake of McCallum's resignation, Jim Nickel, deputy head of mission at the Embassy of Canada in Beijing, will represent the country in China as charge d'affaires effective immediately, the prime minister said.

With files from Mike Blanchfield