US warns citizens of arbitrary exit bans in China

The United States warned its citizens Thursday they could face arbitrary action by authorities when they visit China, following the detention of two Canadians.

Updating its travel advisory, the State Department maintained its previous guidance that Americans should "exercise increased caution" in China and stopped short of discouraging visits.

While the language was largely the same as earlier, the State Department warned of "arbitrary enforcement of local laws," sudden prohibitions on exiting the country and harassment of US citizens of Chinese heritage.

"In most cases, US citizens only become aware of the exit ban when they attempt to depart China, and there is no method to find out how long the ban may continue," it said.

"US citizens under exit bans have been harassed and threatened," it said.

It also advised caution over last-minute security checks and curfews in Xinjiang and Tibet, two minority-dominated regions where Beijing has sought to impose strict control.

China last month detained two Canadians, a former diplomat and a businessman, on charges of activities that "endanger China's security." The move was widely seen as retaliation after Canada arrested an executive of telecom giant Huawei at the request of the United States, which said she violated Washington's sanctions on Iran.

China last year appeared to hit back at the US travel advice by issuing its own guidance to Chinese coming to the United States, warning of the risk of mass shootings and the high cost of health care.

Despite rising political friction, the two countries remain among the top sources of visitors to each other, with China by far the largest provider of foreign students to the United States.