BEIJING (REUTERS, AFP, XINHUA) - Wuhan, the epicentre of the coronavirus outbreak in China, reported on Monday (May 11) its first cluster of infections since a lockdown on the central Chinese city was lifted a month ago, stoking concerns of a wider resurgence of the disease.

The new infections add a layer of caution to the efforts to lower coronavirus-related restrictions across China as businesses restart and individuals go back to work.

Wuhan reported five new confirmed cases, all of whom live in the same residential compound and were mostly older people. One of them was the wife of an 89-year-old male patient reported a day earlier, in the first confirmed case in the city since April 3.

"At present, the task of epidemic prevention and control in the city is still very heavy," said the Wuhan health authority in a statement. "We must resolutely contain the risk of a rebound."

All of the latest confirmed cases were previously classified as asymptomatic, people who test positive for the virus and are capable of infecting others but do not show clinical signs such as a fever.

The number of asymptomatic cases in China is not known, as they only appear on the radar of health officials when they show up positive during tests conducted as part of contact tracing and health checks.

China does not include asymptomatic cases in its overall tally of confirmed cases, currently at 82,918, until they exhibit signs of infection.

Mainland China has reported 4,633 deaths.

Hundreds of asymptomatic cases in Wuhan, which was released on April 8 from a months-long lockdown, are currently being monitored, according to the city's health authority.

The number of new cases reported in China since April have been small compared with the thousands confirmed each day in February, thanks to a nationwide regime of screening, testing and quarantine.

The government said on Friday that China will gradually reopen cinemas, museums and other recreational venues, though restrictions including mandatory reservations and a limit on numbers will be in place.

Shanghai has already reopened some night entertainment venues such as discotheques. Walt Disney Co on Monday reopened its Shanghai Disneyland park, though to a reduced number of visitors.

New outbreaks in China in the past two months have mainly developed in residential compounds or at hospitals.

South Korea is also battling a wave of new cases, although there the most recent outbreaks started in nightclubs and bars.

NORTHEAST CHINA

The Wuhan cases helped push the overall new Covid-19 infections confirmed on Sunday to 17, the highest daily increase since April 28.

Of the new cases, seven were so-called imported cases in the northern Chinese region of Inner Mongolia involving travellers from overseas, compared with two reported a day earlier.

The north-eastern Jilin province, which on Saturday reported a cluster of infections in one of its cities, Shulan, reported three additional local cases.

Shulan has been marked a high-risk area, the only place in China with that designation.

"We're now in a 'war-time' mode," said Jin Hua, mayor of Shulan, which until the weekend had reported no local cases for more than 70 days.

Shulan has imposed a lockdown on its 600,000 residents since the weekend, with just one member of a household being allowed out each day to buy necessities.

One of the three cases confirmed in the province on Sunday was from Shulan.

The other two were from the city of Jilin uncovered through contact tracing of people who were in contact with earlier Shulan cases.

Nearby Liaoning and Heilongjiang provinces each reported one case, adding to worries about a resurgence of the outbreak in the region.

A 70-year-old patient in Harbin, capital of Heilongjiang, had tested negative seven times before results turned positive.

In China, the number of new asymptomatic Covid-19 cases fell to 12 on Sunday, compared with 20 reported a day earlier.

No new deaths have been reported nationwide for nearly a month, with life in China gradually returning to normal after months of disruption.

Authorities in Wuhan had imposed draconian restrictions on travel and movement in January in what appeared to have been a successful bid to quash the outbreak.

That lockdown began to ease in recent weeks, as authorities said the disease was under control, most recently with children returning to school, and travel to and from the city allowed.

The news of new infections in Wuhan comes as many European nations begin the tricky task of navigating out of lockdowns imposed to halt the spread of the virus.

It also comes as swathes of the United States ease restrictions on movement - despite still rising rates of infection - and as citizens chafe under rules many say are government overreach.

Health experts warn that too hasty a return to normal could spark a second wave of infections, and point out that restrictions will have to remain until there is a vaccine.

The virus has now infected more than four million people worldwide - claiming more than 280,000 lives - and crippled the global economy.