Canada's China ambassador John McCallum told an event in Markham, Ontario, on Tuesday, where Chinese-language media were present, that Meng had "some strong arguments she can make before a judge" in fighting extradition, the Canadian Broadcasting Corporation reported.

McCallum was quoted as saying, "One, political involvement by comments from Donald Trump in her case. Two, there's an extraterritorial aspect to her case, and three, there's the issue of Iran sanctions which are involved in her case, and Canada does not sign on to these Iran sanctions. So I think she has some strong arguments that she can make before a judge,"

Meng was arrested in Vancouver on 1 December at the request of US law enforcement under the terms of a bilateral extradition treaty. The US has now said it will make a formal bid to extradite her to face charges of violating its sanctions on Iran.

“If I think it’s good for what will be certainly the largest trade deal ever made – which is a very important thing – what’s good for national security – I would certainly intervene if I thought it was necessary.”

McCallum told his audience: "It's purely a judicial process. There may come a time when the justice minister is required to give a view, but that will not be for some months to come.

"I know this has angered China, but we have a system of extradition treaty, a system of rules of law, which are above the government. The government cannot change these things, and as I said, I think Ms. Meng has quite a strong case."

China has detained two Canadians after Meng was arrested and also re-sentenced a third, and awarded the man the death penalty, in what is seen as retaliation for Meng's arrest.

When Chinese foreign ministry spokeswoman Hua Chunying was asked at a regular press briefing in Beijing on Wednesday whether a US extradition request would affect forthcoming US-China trade talks on 30 January, she said she would not offer any reply to a hypothetical question, seemingly unaware that the US had said on Monday that it would proceed with a formal request.

Hua added: "I have to point out that the US side claimed that its extradition request to Canada is essentially related to the US sanction bills on Iran. But as you may all have known, Huawei for many times has solemnly stated that it complies with all applicable laws and regulations where it operates.

"I want to stress in particular that China holds a consistent position on opposing the US unilateral sanctions on Iran outside the framework of the UN Security Council. What the US has done does not accord with the international law and has been opposed by the whole world, including its allies. The Canadian side is also opposed to that.

"Therefore, the US actions, fundamentally speaking, do not comply with the international law and are not legitimate at all. Its actions are highly political and are in nature scientific bullying.

"The real motive of the US side is clear for all to see, which is leaving no stones unturned in oppressing China's hi-tech companies and depriving China of its legitimate development rights. I believe that whoever that sees things clearly and has a sense of justice should voice their firm opposition to that."

Last year, the US Department of Commerce imposed a seven-year ban on another big Chinese telco equipment maker, ZTE, claiming that the company had made false statements during talks in 2016 over a charge of shipping telco equipment to Iran and North Korea.

ZTE shut down its main business activities in the US on 9 May.

But following the intervention of US President Donald Trump, a deal was worked out for ZTE to return to business by paying a fine of US$1 billion, changing its management team and depositing US$400 million in an escrow account against possible future transgressions.