The infected workers are among almost 300 who had chosen to stay back at the factory of the Long Viet Wooden Technology JSC in the southern province’s Di An Town.

The company had begun accommodating workers on the premises itself on July 10 instead of letting them go back and forth between their residences and the workplace to minimize risks of contracting the virus.

To ensure social distancing among the workers, it decided to reduce production capacity by 40 percent over the normal and laid off around 500 employees so that it could continue operation.

All the workers had tested negative for the virus before beginning their factory stay.

"For now, it’s not clear how the Covid-19 prevention protocol at the factory was breached," said Bui Thanh Nhan, Party chief of Di An Town.

Local authorities have asked the company to submit a detailed report on the matter, he said.

The company had written to the provincial administration, seeking help after too many infections were found at the factory.

As of July 25, more than 3,700 firms with 390,000 workers in Binh Duong had either let employees stay at work or arranged for them to stay in one area to be picked up and dropped off every day, according to official data.

Binh Duong, with 1.2 million factory workers in 29 industrial parks and 12 industrial complexes, has detected more than 8,800 Covid-19 cases so far in the new wave that hit Vietnam three months ago. 2,000 of these have been factory workers.

The province is now the second worst-hit locality after HCMC, which has more than 68,200 cases.