In a first, China has banned four New Zealand Members of Parliament for a year over their visit to Taiwan, New Zealand's foreign ministry says.

The MPs learned of the ban, which the Chinese Embassy said could be reduced or waived with an apology, upon returning from the trip in May, local media reported on Thursday.

China claims the self-governed island of Taiwan as its territory, and has tried to restrict the island's foreign engagements.

But this is the first time China has imposed travel bans on New Zealand MPs for visiting Taiwan - a move that "surprised" foreign minister Winston Peters, a ministry spokesperson said in a statement to the BBC.

"New Zealand MPs have visited Taiwan for decades and such visits are not inconsistent with New Zealand's One China policy," the spokesperson said.

The visit in May comprised lawmakers from the ruling coalition - Maureen Pugh, David Wilson and Laura McClure - as well as Duncan Webb from the opposition Labour Party.

McClure, from the ACT party, said the travel ban was "a type of foreign interference" and that she was "not going to apologise for visiting Taiwan", the New Zealand Herald reported.

She told Radio New Zealand that she was "quite surprised and shocked" by the ban as similar visits had happened for years previously.

She added that New Zealand MPs "have the right to travel freely around the globe".

"That is part of living in a free democracy," she said.

New Zealand foreign minister Peters has instructed foreign ministry officials in Beijing and Wellington to discuss the matter with Chinese authorities to "better understand" the "departure from past practice", the spokesperson said.

New Zealand established formal diplomatic ties with Beijing in 1972 and has since maintained a One China policy - the diplomatic acknowledgement of China's position that there is only one Chinese government. New Zealand has formal ties only with Beijing, and not with Taipei.

But like many countries, New Zealand has also maintained regular exchanges with Taiwan.

Last year, a group of New Zealand MPs met Taiwanese President Lai Ching-te during a trip to Taiwan. The Chinese embassy in New Zealand criticised the trip, describing the MPs as "colluding with 'Taiwan independence' separatist forces".

Beijing also previously condemned a group of New Zealand lawmakers for attending a reception hosted by Taiwan's de facto embassy in Wellington last October.

Taiwan has previously accused China of trying to intervene in its diplomatic ties with other countries.

Last month, Taiwan President Lai Ching-te visited Eswatini - Taiwan's only diplomatic ally in Africa - days after his government said a trip had been cancelled due to China pressuring African countries to bar him from flying over their territories.

That Eswatini visit was later brought up by Taiwan's foreign minister Lin Chia-lung in a post about the New Zealand delegation's visit.

"President Lai's recent visit to Eswatini has once again made the world feel the challenges facing Taiwan's diplomacy," he wrote on Facebook.

Lin further noted that the visit by the New Zealand MPs "not only showed the support of the New Zealand Parliament for Taiwan, but also made the friendship between Taiwan and New Zealand stronger".

China has sanctioned US lawmakers in the past for visiting Taiwan, including former House Speaker Nancy Pelosi in 2022.

The following year, China sanctioned US Representative Michael McCaul, claiming that his visit to Taiwan sent a "serious wrong signal to Taiwan independence separatist forces".