Hong Kong has begun a mandatory two-week quarantine for anyone arriving from mainland China, in a fresh effort to contain the new coronavirus.
Visitors must isolate themselves in hotel rooms or go to government-run centres, while returning Hong Kong residents must stay inside their homes.
Tens of thousands of travelers queued at the Chinese border city of Shenzhen ahead of the midnight deadline as anyone caught flouting the new rules faces a fine and a prison sentence
Hong Kong has seen 26 confirmed cases of the virus and one person has died. The number of confirmed cases in mainland China stands at 34,546, with 722 deaths.
Outside China, 270 cases have been confirmed in at least 25 countries, with one other fatality – in the Philippines.
The semi-autonomous Chinese territory said the mandatory quarantine on anyone entering from the mainland was intended to reduce the spread of the disease.
Tens of thousands of people usually travel from mainland China to Hong Kong every day, although that number fell in recent weeks after the territory closed many of its border points.
This week, thousands of medical workers have been on strike, calling for the border to be fully closed.
Hong Kong authorities said about 11,000 mainland visitors entered the territory on Thursday, up from 8,760 the day before.