VANCOUVER, British Columbia — The reasons that the United States asked the Canadian authorities to arrest a top executive of the Chinese technology company Huawei last week had been shrouded in mystery.

On Friday, the details of the arrest and what led up to it came out in a Canadian courtroom.

At a bail hearing in Vancouver for Meng Wanzhou, the chief financial officer of Huawei and a daughter of the company’s founder, Canadian prosecutors said she was accused of fraud. The heart of the charges related to how Ms. Meng may have participated in a scheme to trick financial institutions into making transactions that violated United States sanctions against Iran, they said.

Ms. Meng had “direct involvement” with Huawei’s representations to banks, said John Gibb-Carsley, an attorney with Canada’s Justice Department.

The hearing shed light on an incident that has rattled the relationship between the United States and China as they prepare to enter negotiations to cease a brutal trade war. While changing planes in Vancouver on Dec. 1, Ms. Meng was arrested at the behest of the United States, which has for years looked into potential ties between Huawei and the Chinese government or Communist Party.