Hundreds of flights were canceled at an international airport in China's southern city of Shenzhen Saturday after a restaurant employee tested positive for the delta coronavirus variant.

Anyone entering the facility must show a negative virus test from the last 48 hours, the Shenzhen Airport Group said in a statement on its official WeChat social media account.

City health officials said a 21-year-old waitress at the Shenzhen Baoan International Airport had been infected with the delta variant of the virus.

The woman tested positive during a routine test for airport staff conducted Thursday, they said.

Shenzhen, a mainland Chinese city neighboring Hong Kong, is home to some of Asia's biggest tech companies including telecoms equipment maker Huawei and gaming giant Tencent.

China on Friday reported 30 new coronavirus cases, including six local transmissions in the southern province of Guangdong where Shenzhen is located.

The airport entry restrictions came into effect from 1 p.m. local time Saturday (5 a.m. GMT).

Nearly 400 flights to and from the airport were cancelled Friday, data from flight tracker VariFlight showed. Dozens of flights scheduled for Saturday morning were also dropped.

Passengers will receive refunds on their tickets without penalty, the airport authority said.

Millions of Shenzhen residents have been tested for the virus in recent weeks after a small outbreak at the city's port earlier this month.