Flight check-in services have been suspended at Hong Kong's international airport, the airport authority said on Tuesday, citing disruptions caused by anti-government protests.
Increasingly violent protests have plunged the Asian financial hub into its most serious political crisis in decades, posing a challenge to the central government in Beijing.
The Airport Authority (AA) halted all flights to and from the airport on Monday, and flag carrier Cathay Pacific Airways Ltd said on Tuesday it had suspended all check-ins.
"Terminal operations at Hong Kong International Airport have been seriously disrupted as a result of the public assembly at the airport today," the AA said, adding that check-in service for departing flights has been suspended since 4:30 pm local time.
In a separate statement, Cathay Pacific said: "There is potential for further flight disruptions at short notice".
Meanwhile, the United Nations High Commissioner for Human Rights Michelle Bachelet urged Hong Hong authorities on Tuesday to exercise restraint and investigate evidence of its forces firing tear gas at protesters in ways banned by international law.
"Officials can be seen firing tear gas canisters into crowded, enclosed areas and directly at individual protesters on multiple occasions, creating a considerable risk of death or serious injury," Bachelet said in a statement.
China's comments on Monday about "sprouts of terrorism" emerging in Hong Kong are not helpful and risk inflaming the situation, her spokesman Rupert Colville told a news briefing.