The parks, Van Trung, Quang Chau, Dinh Tram in Viet Yen District, and Song Khe – Noi Hoang in Yen Dung, with hundreds of companies and 136,000 workers have all recorded cases of infection.

Speaking at an online meeting with companies in the four parks on Monday night, the province's chairman, Le Anh Duong, said the Covid situation had never been so complicated.

Since the new wave of local transmissions began in the country three weeks ago, Bac Giang has registered 411 cases, including 326 in industrial parks.

It is currently quarantining more than 6,000 people for having been in direct contact with infected people and medically monitoring 30,000 others.

It is also speeding up mass testing of all workers at and people living around the four industrial parks.

"To put out the hotspot thoroughly, companies might have to stop operations for one to two weeks," Duong said, warning that otherwise the risk is serious.

Most companies said they do not want such a closure, saying it would cause them significant losses and their customers leave them. But some agreed, saying it is necessary to have a long-term view.

The provincial authorities promised that once the outbreak is brought under control they would have clear plans to support businesses by preventing further infections and guaranteeing safety so that they could safely resume operations.

Bac Giang Province has six industrial parks with more than 240,000 workers, all situated near residential areas and national highways and thus posing a major threat of spreading infection.

By Tuesday morning Vietnam had recorded 1,340 cases of Covid in the new wave that began on April 27.

Of the infected people, 396 are workers in industrial zones in eight cities and provinces, according to the Vietnam General Confederation of Labor.