The Zhuhai special economic zone in South China's Guangdong province has immediately started tracking the activities of three Macao residents in the city after two of them had positive nucleic acid test results, according to a statement released by the city's anti-COVID-19 headquarters on Tuesday.

Meanwhile, relevant departments expanded screening on the target people in the city's airport, exit and entrance ports and other key venues.

A couple from Macao were detected to be positive when they had routine nucleic acid tests while arriving in the city, which borders Macao, on Tuesday.

Their daughter was also found to have arrived at the Zhuhai airport from Macao and took a flight to Xi'an in Northwest China's Shaanxi province on July 19, and returned to Zhuhai airport on July 24 before she took a bus back to Macao.

The couple were found to have entered and left Zhuhai on the same day via Gongbei Checkpoint on July 25 and Friday, Sunday and Monday, respectively.

Meanwhile the statement urged those who had contact with the three Macao residents to report to relevant departments and have their nucleic acid tested to prevent the coronavirus from spreading in Zhuhai.