Residents get tested for COVID-19 at a temporary testing center in Sha Tin district, Hong Kong, Feb 17, 2022. (EDMOND TANG / CHINA DAILY)

HONG KONG -  The Hong Kong government said it has detected 49 preliminary positive COVID-19 cases as it completed a targeted testing operation in Sha Tin on Tuesday morning.

The authorities set up a "restricted area" at Chung Wo House of Chung On Estate at around 2:30 pm on Monday after traces of the coronavirus were found in sewage discharged from the public housing building.

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Residents of the block were required to stay in their premises and undergo compulsory testing until all people in the area were tested and the test results mostly ascertained

In addition, the government set up a "restricted area" at Heng Fung House of Heng On Estate in Sha Tin at around 2:30 pm Tuesday after a resident tested preliminarily positive to a COVID-19 mutant strain and sewage discharged from the block tested positive to the virus

In a statement Tuesday, the government said about 1,170 people have undergone testing in the operation. A total of 49 preliminarily tested positive cases and four indeterminate cases were found and the Centre for Health Protection of the Department of Health will take follow-up action, it added.

Government staff visited about 370 households during the operation, among which 21 did not answer the door, according to the statement.

The authorities reiterated that enforcement actions will be taken seriously. Anyone in the restricted ara "who fails to present an SMS notification with a test result as proof of having undergone testing breaches the compulsory testing notice and may be liable to a fine of HK$10,000," it added.

In addition, anyone who had been stayed in the building for more than two hours from Feb 8 to Feb 21 must undergo compulsory testing on or before Wednesday.

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In addition, the government set up a "restricted area" at Heng Fung House of Heng On Estate in Sha Tin at around 2:30 pm Tuesday after a resident tested preliminarily positive to a COVID-19 mutant strain and sewage discharged from the block tested positive to the virus.

Residents are required to get tested by 10 pm the same day.