Canadian authorities have arrested the chief financial officer of China's Huawei Technologies for possible extradition to the United States.
Meng Wanzhou was arrested in Vancouver, British Columbia, on Saturday, Canada's Justice Department reported.
The Globe and Mail newspaper, citing law enforcement sources, said she was accused of trying to evade US curbs on trade with Iran.
Meng's arrest comes at a time when tensions between US and China are running high over their ongoing trade war, and happened on the same day Donald Trump and Xi Jinping met in Argentina.
Asian stock markets tumbled on the news, fearing renewed US-Chinese tensions that threaten global economic growth.
Telecommunications giant Huawei recently overtook Apple to become the second largest smartphone maker after Samsung.
Meng is also deputy chairman of the Huawei board and the daughter of company founder Ren Zhengfei.
Huawei issued a statement saying Meng was changing flights in Canada when she was detained "on behalf of the United States of America" to face "unspecified charges" in New York.
"The company has been provided very little information regarding the charges and is not aware of any wrongdoing by Ms Meng," the statement said.
Huawei said it complies with all laws and rules where it operates, including export controls and sanctions of the United Nations, the US and European Union.
Huawei Technologies Ltd, the biggest global supplier of network gear used by phone and internet companies, has been the target of deepening US security concerns.
Washington has pressured European countries and other allies to limit use of its technology.
The US sees Huawei and smaller Chinese tech suppliers as possible fronts for Chinese spying and as commercial competitors that the Trump administration says benefit from improper subsidies and market barriers.
The Chinese Embassy in Ottawa responded to Meng's arrest by saying her human rights had been violated and demanded her immediate release.
"At the request of the US side, the Canadian side arrested a Chinese citizen not violating any American or Canadian law. The Chinese side firmly opposes and strongly protests over such kind of actions which seriously harmed the human rights of the victim," the statement said.
A US Justice Department spokesman declined to comment.
In April, China appealed to Washington to avoid damaging business confidence following the Wall Street Journal report that US authorities were investigating whether Huawei violated sanctions on Iran amid spiralling technology tensions.