Ardern apologises for swearing at New Zealand rival

New Zealand's Jacinda Ardern apologised for calling a political rival an "arrogant prick" in parliament on Tuesday, as the prime minister faces a drop in public support.

In the throes of spirited parliamentary debate, Ardern took issue when the leader of an opposition party asked her to give an example of an occasion when she had made a mistake, apologised and fixed it.

The prime minister gave an impassioned, detailed response, then as she sat down muttered "such an arrogant prick" which was picked up by the microphones in parliament.

Seymour, leader of New Zealand's ACT party, objected to the remark lobbed in his direction and petitioned the speaker of the House of Representatives to have it withdrawn.

Ardern's office later said she had apologised.

The 42-year-old has been prime minister for five years, and has won favour worldwide for her management of crises and down-to-earth approach to politics.

She was one of the first prime ministers to become a mum while in office and has enjoyed sky-high approval ratings for most of her two-term tenure.

But with New Zealand expected to go to the polls in late 2023 and the cost of living skyrocketing, she is under increasing political pressure.

Support for her Labour party appears to be waning with the latest opinion polls showing them trailing the opposition party National by five percentage points.