It urged commuters to consider staying back at their workplace or renting apartments nearby to avoid going back and forth between the localities to prevent the risk of spread of infection.

"If they cannot arrange to stay put and have to travel between HCMC and Dong Nai or Binh Duong and Dong Nai every day, they must produce a certificate that they tested negative," Dong Nai People's Committee said in a statement.

The certificate will only be valid for seven days from the date of issue. The requirement takes effect on July 5.

A task force will man checkpoints set up at the province’s borders and scrutinize the certificates.

Many companies in the three places have begun to offer accommodation for their workers in makeshift dormitories or by renting apartments.

HCMC is the second worst hit locality in the ongoing wave that broke out in the country two months ago.

By Wednesday morning it had 3,653 infections while neighboring Binh Duong had 326.

Dong Nai has now reported 19 cases, including 17 linked to HCMC and one to Binh Duong.

The three localities house a large number of factories. Dong Nai is home to 1.2 million workers, including 620,000 in its 32 industrial parks.

Early in June it mandated 21 days of self-quarantine for travelers from HCMC, but rescinded the requirement within 12 hours.

Officials and businesses had expressed concern the quarantine requirement would be disruptive since around 16,000 people travel between the two places daily.