HANOI (REUTERS) - Vietnam said on Thursday (April 29) it had detected its first locally transmitted cases of the coronavirus in 35 days, as the authorities ordered tighter surveillance to prevent a new outbreak.

Four members of a family in the northern Ha Nam province and one person in southern Ho Chi Minh City were infected, the health ministry said, having all been in contact with an individual who had returned from Japan and tested positive, despite clearing quarantine.

Authorities ordered provinces and state agencies to tighten screening and controls and contact-tracing efforts were launched after the community infections were found, state broadcaster Vietnam Television reported.

With its strict quarantine and tracking measures, Vietnam has successfully contained its three outbreaks of the virus so far and now is ramping up measures to prevent a fourth, as other countries in the region see sharp rises in cases.

The South-east Asian nation of nearly 98 million people has reported just 2,910 cases and 35 deaths overall, one of the best records in Asia, owing to its quick response to outbreaks.

The infections come ahead of four days of holidays that begin on Friday and as neighbouring Laos and Cambodia and nearby Thailand report big jumps in cases.