Foreign Affairs Minister Winston Peters has defended sending two friends on a taxpayer-funded trip to Antarctica, calling it an "appalling, racist attack".
Peters said Bee Lin Chew and her daughter Su Arn Kwek went on the trip as part of efforts to raise $50 million from donations to redevelop Scott Base.
They have not yet made any donations to the programme.
Act leader David Seymour, who got into a Twitter spat with the Deputy Prime Minister this week, said sending the women on the trip "was absolutely an abuse of power by Winston Peters".
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Finance Minister Grant Robertson was initially meant to go on the February 7-10 trip at the start of February but had to pull out due to the timing of Waitangi Day and the first sitting week of Parliament.
Emails released under the Official Information Act, sent to the Herald, show Peters insisted the women go in his place, which left officials scrambling as there was only one spot.
Antarctica New Zealand initially warned that science programmes or essential staff may have to be cut to make room for the women but were able to fulfil the request without disrupting the programme.
The women, who are dual Malaysian-New Zealand citizens, are connected to one of South East Asia's richest families.
Chew told RNZ she was a good friend of Peters and his partner Jan Trotman.
Peters today called reports about the women's trip "an appalling, racist attack" on two people who could be helping the Scott Base programme.
"I despise this racist attack on innocent people."
Peters said he presented Cabinet with a proposal on June 4, 2019, for a $250 million redevelopment of Scott Base - of which $50 million was to be raised from public donations.
He was asked by media if the women would have been invited if they weren't his friends and replied: "I've had countless people and members of Parliament in their droves have been down there.
"Dare I say it, I've seen fourteen journalists go on the trip. Could you please tell me what they did for Antarctica? At least my plan has a hope of finding the $50 million."
Prime Minister Jacinda Ardern said she hadn't spoken to Peters about the women's trip but will be seeking assurances from him about the integrity of the Antarctica programme.
"It's clear though that there's no interest for the Minister here. He wants the redevelopment in Scott Base, it obviously comes at a reasonable sum and they're drawing on a range of sources for that."
Seymour said the trip was an "abuse of power" by Peters and should be investigated - but that was unlikely before the election.
"Winston Peters has just become a joke. That's taxpayer money for a good purpose and he's just laughing at the New Zealand taxpayer. I think that's why he needs to be gone," Seymour said.
"I think it's just commonsense that he always talks about. That taxpayer money is for exploring relationships in Antarctica, not for him to give jaunts to his mates."
The Act leader said he was firstly surprised Peters "had any friends left".
"But second of all, it's borderline corruption. It's unacceptable in a country with the reputation of New Zealand and I have to ask what is their friendship really based on?"
Seymour later called on Ardern to "release the paper trail" to show the reason for the women's trip was philanthropic.
""I asked the Prime Minister to explain to the House the process used to select potential philanthropists who might support Scott Base for a trip to Antarctica. She wasn't able to.
"The Prime Minister ducked and dived around the idea that there should be philanthropic funding, but completely failed to explain how the Government had selected Ms Chew and Ms Kwek as potential philanthropists, leaving their friendship with Mr Peters as the only publicly-known explanation."