HANOI -- Vietnam's Prime Minister said on Wednesday that the next 10 days would be critical in the Southeast Asian country's fight against a new coronavirus outbreak, which resurfaced late last month after three months of no domestic cases.

Vietnam was lauded for suppressing an earlier contagion through aggressive testing, contact-tracing and quarantining, but it is now racing to control infections in multiple locations linked to the popular holiday city of Da Nang, where a new outbreak was detected on July 25.

"Note that the period from this week to the middle of next week is critical," Prime Minister Nguyen Xuan Phuc said on Wednesday, according to a government statement.

"Which measures should we continue to implement to win against the virus? Which lessons have we learnt from this current outbreak?" said Phuc.

Vietnam reported 17 new coronavirus infections on Wednesday, including three imported cases, according to the Ministry of Health.

The country's coronavirus tally has hit 880 as of Wednesday evening, with 400 recoveries and 17 deaths. All fatalities stemmed from the new outbreak.

The majority of recent cases were in Da Nang, a town of 1.1 million, where broad social distancing measures were extended indefinitely on Wednesday.

A sports stadium converted into a 1,000-bed field hospital received its first COVID-19 patients on Wednesday, many of them from three urban hospitals at the center of Da Nang's outbreak.

Phuc characterised actions taken by the authorities to combat the current, third wave of infections as better than previous outbreaks.

People in Vietnam had also reacted more calmly, despite the sudden re-emergence of the virus, Phuc said.

He had previously said early August would be the decisive time within which to stop the virus spreading in Vietnam on a large scale.