New local Covid-19 infections have more than doubled in China's southeastern province of Fujian, health authorities say, in the country's latest outbreak of the novel coronavirus.

The National Health Commission said 59 new locally transmitted cases have been reported for September 13, up from 22 infections a day earlier, reports Reuters. All of them are in Fujian.

In just four days, a total of 102 community infections have been reported in Fujian, a province bordered by Zhejiang to the north and Guangdong to the south.

Fujian's outbreak began in Putian, a city of 3.2 million, with the first case reported on September 10. Preliminary tests on samples from some Putian cases showed patients had contracted the highly transmissible Delta variant.

The virus has since spread to the scenic coastal city of Xiamen, which reported 32 new local cases for September 13 compared with just one infection a day earlier.