New Zealand Prime Minister Jacinda Ardern, who has overseen her country's world-leading response to the coronavirus pandemic, has tested positive for Covid-19, her office announced Saturday.

Ardern's symptoms are moderate and she will isolate at home for seven days, the government said in a statement.

She has already been in isolation since last Sunday, when her partner Clarke Gayford tested positive, and was due to resume her parliamentary duties on Monday.

New Zealand enforced one of the world's most restrictive approaches to managing the initial Covid-19 outbreak in 2020, and its death toll of 892 remains among the lowest of developed nations.

However, it has experienced an Omicron surge since restrictions were loosened in March, with Ardern's positive case among more than 50,000 recorded over the last week.

The statement said Ardern's arrangements for her upcoming trade mission to the United States are unaffected.

Details of the trip are still to be confirmed, although she is scheduled to deliver the commencement address at Harvard University on May 26.

Ardern will not be present in parliament for two high-profile domestic announcements -- the release of the government's emissions reduction plan on Monday and the unveiling of the annual budget on Thursday.

"This is a milestone week for the government and I'm gutted I can't be there for it," Ardern said.

"Our emissions reduction plan sets the path to achieve our carbon zero goal and the budget addresses the long-term future and security of New Zealand's health system.

"But as I said earlier this week, isolating with Covid-19 is a very Kiwi experience this year and my family is no different."

Ardern shared a photo of her positive test on Instagram.