MONTREAL — Canada’s ambassador to China has resigned following a series of diplomatic missteps that further complicated already strained relations between the two countries.

The resignation came days after the ambassador, John McCallum, stunned seasoned diplomatic observers by saying that Meng Wanzhou, the chief financial officer of the Chinese telecom firm Huawei who was arrested in December by Canadian authorities in Vancouver at the United States request, stood a good chance of avoiding extradition to the United States.

His public assessment of the sensitive and high profile case came under sharp criticism, including from the leader of the opposition conservative party Andrew Scheer, who said Mr. McCallum’s comments threatened to politicize the case and called for him to be fired.

“Last night, I asked for and accepted John McCallum’s resignation as Canada’s ambassador to China,” Prime Minister Justin Trudeau said Saturday.