Green Party COVID-19 spokesperson Elizabeth Kerekere's isolation rule breach was discovered by her "disappointed" co-leader Marama Davidson.
Dr Kerekere apologised "profusely" on Tuesday after admitting to breaching COVID-19 rules by catching a regional flight days after a member of her household tested positive for the virus.
Dr Kerekere said her household member tested positive on Friday, meaning as a household contact she should have self-isolated for seven days, but the Green MP instead caught a flight from Tairāwhiti to Wellington.
Dr Kerekere said she tested negative for three consecutive days using rapid antigen tests (RATs), but since she is not classified as an essential worker, the Green MP did not have the right to return to Parliament on Monday as a household contact of a COVID-19 case.
"I apologise profusely to my constituents, whānau, and colleagues for my mistake, and to everyone who is making huge sacrifices to follow rules that are designed to keep us all safe," Dr Kerekere said in a statement on Tuesday.
"I have discussed my mistake with the Green Party caucus and our co-leaders, and apologised to them also. I should have known better.
"Today I have resigned my COVID-19 Response portfolio with immediate effect, and I will not hold the health portfolio or sit on the Health Select Committee until further notice."
Davidon said Dr Kerekere was sent to her apartment to self-isolate.
"She has admitted and apologised for the mistake and we understand that it's really important that everybody including MPs uphold the rules that were put in place for public health and safety," Davidson told reporters on Tuesday.
"It became clear to us yesterday that she had left as a household contact and we immediately took action as soon as that became clear to us.
"We needed to make sure that we also had the time to work through our action and bring the caucus up to speed which was done at this morning's caucus meeting.
"She was told to leave the precinct and isolate immediately in her apartment."
Davidson confirmed that she discovered Dr Kerekere's rule breach.
"She highlighted a situation and then it became clear to me yesterday that it was a breach of the rules," she said.
"I am disappointed. Any MP should know better but of course a COVID-19 spokesperson should absolutely know the rules. We've expressed that disappointment."
Davidson said Dr Kerekere offered to stand down from her COVID-19 portfolio at the Green Party's caucus meeting on Tuesday morning. The caucus then decided to strip her of the health portfolio too.
"We want people to see we are accountable to the public and MPs are treated like anyone else breaching the health orders."
Green MP Teanau Tuiono will become COVID-19 spokesperson while Green MP Jan Logie will take on health.
Davidson said Dr Kerekere's rule breach has been reported to authorities and her fate as an MP will depend on what, if any, action is taken.
Davidson said it "appears" Dr Kerekere was confused by the COVID-19 rules.
"She has been testing with RATs everyday negatively and she felt that was justification enough to come to Parliament," she said.
"We're very clear that was wrong, that was a mistake, and that she should have known better."
The final phase of the Government's Omicron plan came into effect on February 24 and meant that only household contacts need to self-isolate.
The Government then announced last week that the isolation period for COVID-19 cases and household contacts had been slashed to a week, down from the previous 10 days.
But household contacts still need to have a rapid antigen test at day three and day seven of their isolation period. If they become symptomatic they should also get a test, and if the result is positive, they are required to be isolated for seven days from that point.
Prime Minister Jacinda Ardern said she wasn't fully aware of the details, but suggested MPs should know better.
"We all know that we're held by a high bar and high standard and we only expect of course that all MPs follow the same rules that we ask of the public," she told reporters.
Ardern knows only too well after former Health Minister David Clark stood down from the role in 2020 after breaching COVID-19 lockdown rules by going mountain biking, driving 20km to the beach, and moving house.
