New Zealand recorded its first locally transmitted case of Covid-19 in six months on Tuesday, sparking efforts to trace the origins of the infection as officials pondered a response.

The health department said the case was identified in Auckland, the country's largest city, adding "a link between the case and the border or managed isolation is yet to be established".

It said ministers would meet later Tuesday to determine how to respond to New Zealand's first community case since February 28.

"A hard and early response is the best tool to stamp out any potential spread and everyone in New Zealand is asked to stay calm, be kind and play their part while we gather more information on the potential case," the department said.

Further details of the case were not released.

New Zealand has won widespread praise for its coronavirus response, recording just 26 deaths in a population of five million.

But its vaccine rollout has been less stellar, with only around 20 percent of the population fully inoculated.

Auckland has been forced into several brief periods of lockdown since an initial nationwide response last year succeeded in largely halting the virus at the border.

The most recent stay-at-home orders in the city of two million ended in March.

Officials warned last week that the presence of the Delta variant in New Zealand would trigger "a short, sharp lockdown".

Japan to expand virus emergency

Japan's government said Tuesday it will expand a coronavirus state of emergency to seven new regions as it battles a record wave of infections a week before the Paralympic Games.

Virus emergency measures that ban restaurants and bars from selling alcohol and require them to close by 8 pm are already in place in Tokyo and five other regions, and had been due to end by August 31.

But the government will now expand the measure to additional areas, with the restrictions in all parts of the country running until September 12.

"(Infection) is spreading across Japan on a scale we have never experienced before," said Yasutoshi Nishimura, the coronavirus response minister.

"The number of patients in serious condition is rising each day," he said at an expert meeting.

In addition to the measures affecting bars and restaurants, the government will ask large shopping malls and department stores to limit the number of customers inside at one time.

Japan has seen a smaller outbreak than many other countries, with around 15,400 deaths despite avoiding lockdowns.

But its inoculation programme began later and more slowly than in many other developed countries, and only around 37 percent of the population is currently fully vaccinated.

In recent days, Japan has reported more than 20,000 daily cases nationwide, a record for the country.

The surge began before the Olympics opened last month and continued throughout the Games, which were held with spectators banned from most events.

On Monday night, organisers said a spectator ban would also be applied to the Paralympics, with limited exceptions for a programme bringing schoolchildren to watch the Games.

Paralympic participants face virus restrictions including regular testing and limits on their movement.

The government says there is no evidence that holding the Games contributed to the rise in cases and recent polls have found most Japanese believe holding the Olympics was a good idea, though many also think it fuelled the infection surge.

Some experts argue that the massive international event undermined the government's virus restrictions, encouraging people to go out and businesses to remain open.

Local media reports have estimated up to 40 percent of bars and restaurants in some parts of Tokyo are flouting the virus rules.