A worker at the international airport in Guangzhou, Guangdong province, tested positive for COVID-19, sources in the local health authority said on Tuesday.

The confirmed case was found on Monday during routine testing of staff working at a high-risk post at the entry port of international flights at the Guangzhou Baiyun International Airport, the sources added.

The male worker, 36, had light symptoms of the infection and was sent to the Guangzhou Eighth People's Hospital for medical observation and treatment.

The man, who had been living since early June in a closed-loop management area for workers in high-risk posts at the airport, tested negative between June 3 and 18.

The man had no social activities since closed-loop management was implemented, an initial investigation found.

In another development, five cross-border truck drivers tested positive for COVID-19 between June 17 and 20 at ports in Shenzhen, which borders Hong Kong, according to the Shenzhen health authority.

In Zhuhai, a coastal city in western Guangdong, a citywide mass test was organized on Wednesday, after the city reported a confirmed case and an asymptomatic carrier from neighboring Macao on Tuesday, the local government source said.