Meng Wanzhou, the chief financial officer of Huawei who is facing an extradition request from the US, was illegally held and interrogated by Canadian officers for three hours before being formally arrested, according to a lawsuit filed late last week.

Ms Meng was detained at Vancouver International Airport in December while transferring to an onward flight to Mexico. Her case sparked a political furore in China, where she is widely seen as the victim of a political vendetta by the US.

The lawsuit, filed on Friday and distributed to journalists by Ms Meng’s lawyers on Sunday, alleges that Canadian officers held her on the pretext of making a routine border and immigration inspection. That allowed them to interrogate her, as well as search her luggage and electronic devices, without affording her the rights to a lawyer and other protections that come into play when a suspect is formally arrested.