Seoul, South Korea's two largest electronics firms Samsung Electronics and LG Electronics on Wednesday decided to temporarily shut down their research labs after their workers tested positive for the new coronavirus.

Samsung said it shuttered a mobile research lab in Suwon, just south of Seoul, after a worker there tested positive for COVID-19 on Tuesday.

The company said it has ordered all employees at the building to work from home, while the floor where the virus-infected employee worked will be shuttered through Friday, reports Yonhap news agency.

The world's largest memory chip and smartphone maker previously reported virus cases at its research center in Seoul, and plants in Yongin, Gyeonggi Province, and Gumi, North Gyeongsang Province.

LG also reported that a worker at its research campus in southern Seoul tested positive for COVID-19 and the building will be closed through Thursday.

LG said employees who have come in close contact with the virus-infected worker have been ordered to work from home for two weeks regardless of their test results.

Meanwhile, South Korea's new virus cases soared to the highest level since late August after 313 more COVID-19 infections were confirmed on Wednesday.