China has demanded that Canada release the arrested Huawei executive Meng Wanzhou or face consequences.
Vice Foreign Minister Le Yucheng had summoned the Canadian ambassador and lodged a “strong protest”, a statement said.
The ministry described Ms Meng’s arrest as “extremely nasty”.
Ms Meng, Huawei’s chief financial officer and daughter of the firm’s founder, is accused of breaking US sanctions on Iran.
She was held in Vancouver last Saturday and faces extradition to the US, where she could be jailed for up to 30 years if found guilty.
China insists that she has not violated any laws.
On Friday Ms Meng appeared before a Canadian court, which adjourned a decision on whether or not to allow bail until Monday.
What has China said?
Ms Meng’s arrest while she was changing planes in Vancouver last Saturday was a serious breach of her rights, Reuters quoted the foreign ministry as saying.
It “ignored the law” and was “unreasonable”, it said.
“China strongly urges the Canadian side to immediately release the detained person… otherwise Canada must accept full responsibility for the serious consequences caused,” the statement added.
What happened during Friday’s court appearance?
The Supreme Court of British Columbia was told that Ms Meng had used a Huawei subsidiary called Skycom to evade sanctions on Iran between 2009 and 2014.
The court was told that she had publicly misrepresented Skycom as being a separate company.
A Canadian government lawyer said Ms Meng was accused of “conspiracy to defraud multiple financial institutions”.
He said she had denied to US bankers any direct connections between Huawei and SkyCom, when in fact “SkyCom is Huawei”.
The lawyer said Ms Meng could be a flight risk and thus should be denied bail.
Why was the arrest significant?
The arrest has put further strain on US-China relations. The two countries have been locked in trade disputes, although a 90-day truce had been agreed on Saturday – before news of the arrest came to light on Wednesday.
Huawei is one of the largest telecommunications equipment and services providers in the world, recently passing Apple to become the second-biggest smartphone maker after Samsung.
Canadian Foreign Minister Chrystia Freeland said on Friday that China had been assured that due process was being followed and Ms Meng would have consular access while her case was before the courts.
Ms Freeland reiterated Prime Minister Justin Trudeau’s claim that Ms Meng’s arrest had “no political involvement”.