New Zealand closed its borders to all foreigners from midnight on Thursday, as it stepped up efforts to contain the spread of the coronavirus in the country.

Prime Minister Jacinda Ardern told a press conference that citizens and permanent residents can still return, but their options are running out as many commercial airlines are cancelling flights.

"We will no tolerate risk at our borders," Ardern said at a news conference, adding that borders will remain open for freight and cargo and urged people not to panic-shop.

New Zealand has so far confirmed 28 cases of the coronavirus.