Authorities in southern China have apologised for breaking into the homes of people who had been taken to a quarantine hotel in the latest example of harsh coronavirus prevention measures that have sparked a rare public backlash.

State media said that 84 homes in an apartment complex in Guangzhou city’s Liwan district had been opened in an effort to find any “close contacts” hiding inside and to disinfect the premises.

The doors were later sealed and new locks installed, the Global Times newspaper reported.

The Liwan district government apologised on Monday for such “oversimplified and violent” behaviour, the paper said. An investigation has been launched and “relevant people” will be severely punished, it said.

China’s leadership has maintained its hard-line “zero-Covid” policy despite the mounting economic costs and disruption to the lives of citizens, who continue to be subjected to routine testing and quarantines, even while the rest of the world has opened up to living with the disease.

Numerous cases of police and health workers breaking into homes around China as part of Covid-19 measures have been documented on social media.

In some, doors have been broken down and residents threatened with punishment, even when they tested negative for the virus.

Authorities have demanded keys to lock in residents of apartment buildings where cases have been detected, steel barriers erected to prevent them leaving their compounds and iron bars welded over doors.

China’s Communist leaders exert stringent control over the government, police and levers of social control. Most citizens are inured to a lack of privacy and restrictions on free speech and the right to assembly.

However, the strict Covid-19 measures have tested that tolerance, particularly in Shanghai, where a ruthless and often chaotic lockdown spurred protests online and in person among those unable to access food, healthcare and basic necessities.

Authorities in Beijing have taken a gentler approach, concerned with prompting unrest in the capital ahead of a key party congress later this year at which president and party leader Xi Jinping is expected to receive a third five-year term amid radically slower economic growth and high unemployment among college graduates and migrant workers.

A requirement that only vaccinated people could enter public spaces was swiftly cancelled last week after city residents denounced it as having been announced without warning and unfair to those who have not had their jabs.

China’s national borders remain largely closed and although domestic tourism has picked up, travel around the country remains subject to an array of regulations, with quarantine restrictions constantly in flux.

In one recent incident, some 2,000 visitors to the southern tourist hub of Beihai have been forced to prolong their stays after more than 500 cases were found and they were barred from leaving.

The local government was struggling to find hotel rooms for those who had already prepared to return home, while hotels and airlines were providing refunds for those who had booked holidays to the city that had to be cancelled.

China regulates travel and access to public places through a health code app on citizens’ smartphones that must be updated with regular testing. The app tracks a person’s movements as a form of contact tracing, allowing a further imposition of public monitoring.

The measures remain in place despite relatively low rates of infection. The National Health Commission on Tuesday announced just 699 new cases of domestic transmission detected over the previous 24 hours, the bulk of which were asymptomatic.