Health authorities said the case was a 53 year-old woman who was a close contact of a soldier who contracted the virus at a quarantine facility in Nadi.
“To aid rapid contact tracing and reduce the likelihood of further transmission, we are announcing a lockdown of the greater Nadi and Lautoka area, starting from 4:00am this morning,” the health department said in a statement.
Fiji has largely contained the virus through strict isolation measures and border controls, recording less than 100 cases and just two deaths in a population of 930,000.
More than 330 people who came in contact with the woman were placed in isolation and police were enforcing a 24-hour curfew in Lautoka and Nadi.
Fijians outside the lockdown areas were also advised to stay home, although the measure was not being enforced by authorities, while schools and businesses were closed.
“All Fijians should stay home. Public gatherings should not happen. No services should run except for essential medical services,” the health department said.
Lautoka is Fiji’s second largest city and Nadi was its international tourist hub before borders were closed last year due to the pandemic.
The latest outbreak is a blow for Fiji’s hopes of opening quarantine-free travel bubbles with Australia and New Zealand, the source of most of the country’s international visitors.
Australia and New Zealand on Monday opened a trans-Tasman bubble allowing quarantine-free travel between the two countries.