An imported case of the highly transmissible Omicron variant of COVID-19 was confirmed on Tuesday in Guangzhou, Guangdong province, the local health authority reported. It is the first time the variant was detected in the city.

The patient, a 67-year-old male, had taken a flight back to Guangzhou on Dec 11, after being quarantined outside the city after spending time overseas.

He tested positive on Monday morning during home quarantine and was immediately sent to Guangzhou No 8 People's Hospital for treatment.

The city's center for disease control and prevention carried out a complete genome sequencing and analysis.

"After checks by the provincial centers for disease control and prevention, the patient was confirmed as with the Omicron variant," said Che Bin, deputy director of the Guangzhou health commission.

Local authorities have tightened control measures, including the closing of designated areas, and are requiring people living in nearby areas to be tested.

"We will optimize and adjust the prevention and control measures to strengthen the screening of people coming from affected areas," Chen said. "The Omicron variant has increased the uncertainty of the situation."

As of Tuesday at noon, local authorities had collected 9,196 test samples from residents living in closed and protected areas, all of which were negative, Chen said.