It was imposed after the country's first cases of Covid-19 were detected in Fiji's second-largest city.
Health minister Ifereimi Waqainabete told a news conference on Wednesday the extension is necessary to prevent any further outbreak .
He said authorities will conduct intensive testing that will involve house visits and mobile testing stations.
"We know these restrictions have not been easy for many within the Lautoka confined area. But take comfort in knowing that these tough decisions we're making could very well spare us enormous future suffering," he said.