Canadian Prime Minister Justin Trudeau says his government had no involvement in the arrest of a top executive from Chinese telecoms giant Huawei.
Meng Wanzhou, Huawei's chief financial officer and the daughter of its founder, was detained at Vancouver airport on a US extradition request.
China has demanded her release, calling the arrest a human rights violation.
The charges have not been made public. Huawei said it was "not aware of any wrongdoing by Ms Meng".
She faces a bail hearing on Friday.
The arrest comes at a sensitive time for US-China relations. The nations are locked in a trade war that has seen both impose duties on billions of dollars of one another's goods.
Ms Meng was detained on Saturday, the same day US President Donald Trump and China's President Xi Jinping met at the G20 summit in Argentina and later reached a temporary truce in their trade battle.
But the arrest has angered China and threatens to inflame tensions with the US.
Earlier reports suggested that Ms Meng's arrest could be related to a US investigation into a possible violation of sanctions against Iran.
US National Security Adviser John Bolton declined to comment on this when questioned by journalists.
Instead he said that - generally speaking - he had "enormous concerns" over Chinese firms' business practices and their possible operations as "arms" of the government.