BEIJING (REUTERS) - Cities in China's most populous province of Guangdong have locked down compounds and streets and ordered some travellers to furnish negative Covid-19 test results, as health officials battle to control outbreaks.

All 10 of China's locally confirmed mainland cases for June 1 were in Guangdong, the National Health Commission said on Wednesday (June 2), seven in the provincial capital Guangzhou and three in nearby Foshan city.

China's manufacturing and export hub and its biggest province by economic output, Guangzhou has stepped up coronavirus prevention and control efforts since the latest wave of cases struck in late May.

It has reported 41 locally confirmed cases between May 21 and June 1, and Foshan six cases.

The two cities have ordered residents in some neighbourhoods to be quarantined at home, and required people leaving the cities by plane, train or long-distance bus to show proof of a negative Covid-19 test within three days.

The cases have spurred some Guangzhou residents with no advance appointments for Covid-19 vaccine shots to converge at inoculation venues.

Crowds at some sites have been "severe", Mr Zhang Zhoubin, a Guangzhou disease control official, told reporters on Tuesday.

Guangzhou has suspended individual appointments and made key groups a vaccination priority, so as to ensure adequate numbers of medical staff.

The provincial city of Maoming detected an asymptomatic infection on May 25 that proved to have been in contact with a confirmed patient in Guangzhou.

Officials of Sinopec's Maoming refinery, one of China's biggest, said they had imposed stringent Covid-19 measures and were urging staff to get vaccinated as soon as possible. All its workers at the Maoming port have been vaccinated.

Travel restrictions

Mainland China reported 24 new coronavirus cases on June 1, compared with 23 a day earlier, and 19 new asymptomatic cases, compared with 15 a day earlier. China does not classify symptomless infections as confirmed cases.

The tech hub of Shenzhen, also in Guangdong, saw two new local asymptomatic infections on June 1, raising the total number of asymptomatic cases in the city since May 21 to 15.

On Wednesday people were told to stay away from the environs of a normally-bustling clothing wholesale centre in the city's commercial area of Dongmen, with testing ordered for its staff after an asymptomatic case detected there.

Shenzhen airport has required travellers departing from the airport who hold identity documents from Guangzhou or Foshan to show negative results of virus tests taken within three days prior to travel.

The recent infections in Guangzhou were of a fast-spreading virus strain first detected in India, an official with the city's health authorities said on Sunday. Officials are still investigating the source of the outbreak.

The Shenzhen outbreak is unrelated to the Guangzhou outbreak. Officials there suspect the virus was transmitted to local communities by port workers, with 11 cases infected with a strain spreading in Britain.

Maoming city, also in Guangdong province, detected an asymptomatic infection on May 25, a contact of a confirmed patient in Guangzhou.

As of June 1, China had a total of 91,146 confirmed Covid-19 cases, while its death toll remained unchanged at 4,636.