China has reported a sudden surge of Covid-19 in the country's south, with 20 new local cases on May 30, as authorities locked down areas of Guangdong province's capital city, Reuters reports.

Of the 27 new coronavirus cases reported by the national health authority in its daily updates, only seven infections were imported, with the remainder originating in Guangdong province.

On Saturday, authorities in the capital city of Guangzhou ordered residents on five streets in the city's Liwan district to remain at home and suspended non-essential activities, while entertainment venues and markets were closed.

People leaving the city from airports, train stations and shuttle bus stations need to show proof of a negative Covid-19 test within three days, with exception for travellers who arrive in the city in transit, the city said in a statement.