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 was detained at Vancouver airport on Saturday on an extradition request from the US.
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.
Earlier reports suggested the 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.
European shares hit a two-year low and indexes across Asia dropped sharply following the arrest, which analysts said revived worries over the US-China trade war.
However, the three main US indexes regained some ground by the end of the day, with the Nasdaq closing higher.