Hong Kong is facing an outbreak of Covid-19 among prisoners and is moving infected inmates to an isolation facility as the city struggles to cope with a record number of cases by implementing China’s “zero tolerance” strategy.

The Correctional Services Department said on Thursday that the Sha Tsui facility on Lantau Island has been designated for quarantining infected prisoners, whose numbers are expected to grow.

Seven prisoners have tested positive for Covid, while the number of confirmed cases in the southern Chinese financial hub of about 7.5 million people hit 4,285, double the daily average reported earlier in the week.

Healthcare facilities in Hong Kong are beginning to overflow, and the city’s Caritas Medical Centre was forced to treat patients in beds outside the hospital. Others were waiting in tents to be admitted.

People who test positive are required to quarantine either in hospital if they have serious symptoms or in government-run facilities for light or asymptomatic cases.

China’s leader, Xi Jinping, has ordered the central government to provide Hong Kong with resources to stabilise the outbreak, including rapid antigen tests, medical expertise and supplies.

China has managed major outbreaks through its strict “zero tolerance” policy which involves quarantining incoming travellers, total lockdowns, extensive contact tracing and mass testing millions of people.

Hong Kong leader Carrie Lam has stuck to the same strategy despite the city’s greater population density, higher incomes and more service-oriented economy than in mainland China.

Last week, the entire upmarked Discovery Bay neighbourhood of Hong Kong was ordered to undergo testing after authorities found traces of the virus in its sewage.