United Airlines and American Airlines have suspended flights to and from Hong Kong amid the city’s new mandatory testing rules for airline crew members, according to a report from Bloomberg.

On Tuesday, Hong Kong’s Centre for Health Protection (CPH) said airline crew members arriving in the city will be subjected to mandatory Covid-19 testing starting Wednesday (July 8). CPH added that “deep throat saliva specimens” will be collected, and anyone who refuses to be tested will be subjected to a fine and imprisonment.

If a crew member tests positive, “hospital admission will be arranged as soon as possible.”

United’s service between Singapore and San Francisco via Hong Kong was scheduled to resume on Wednesday. The airline’s website now shows that flights UA 877 and UA 862 have been cancelled.

American Airlines, which was expected to restart passenger services to Hong Kong this week, cancelled flight 125 due to depart Dallas/Fort Worth on Thursday. Flights between Dallas/Fort Worth and Hong Kong will remain suspended through August 5.

“We’ve been making regular adjustments to our schedule to match demand, and we consider a range of factors including travel restrictions or entry requirements in making network decisions,” a spokesperson from the US carrier said in a statement.

Business Traveller Asia-Pacific has asked United when it plans to resume services to Hong Kong.