Ardern again refused to be drawn into the scandal enveloping the National Party, declining to comment on reports that a woman allegedly harassed by MP Jami-Lee Ross signed a confidentiality agreement.
"As I've maintained through much of this, those are ultimately matters for the National Party and for the National Party to answer."
Asked whether there should be an investigation into "cash-for-candidate" allegations levelled at National following the release by Ross of a recording of a discussion between him and leader Simon Bridges, Ardern said: "It is all incumbent on each of us as political parties to make sure that we maintain the law and act appropriately."
Ardern said a select committee could potentially look at whether electoral laws were robust enough.
"Obviously, we have in place electoral laws which are meant to give transparency and meant to give people faith in our systems. We have the ability to review whether or not
they are fulfilling those expectations every time we look at a general election.
"Select committee is doing that soon and they've got plenty of scope to look into some of those issues if they choose to, but we do have robust electoral laws in New Zealand," Ardern said.
"Each of us have to take responsibility for our own parties, our own leadership. My job is to look after the Government and look after the Labour Party."
The taped conversation between Bridges and Ross opened National up to accusations of a cash-for-candidates policy, prompting the Green Party to call for sweeping changes to political donations.
The conversation about a $100,000 donation to the National Party, following a dinner with Zhang Yikun and Colin Zheng, also traversed how to include another Chinese MP in the caucus.
"Now there's no catch or anything to it. You may recall at the dinner they did discuss candidacy, and another Chinese candidate," Ross said in the recording, also noting that Zheng had signed up for candidates' college.
Bridges then talks about getting rid of some current MPs to make way for new ones, adding that it is "bloody hard, you've only got so much space ... Two Chinese [MPs] would be nice".
Bridges said yesterday he did not believe they discussed candidacy at the dinner and he denied National Party list places were for sale.
"We have incredibly robust processes to become a Member of Parliament. It involves selection processes and competition ... and what that's about is the best man or woman winning the job on their merits."
His comments were supported by National MP Melissa Lee, who said: "I did not pay to actually get here, and I don't think anyone else has either."
But Green Party co-leader Marama Davidson said the recording suggested that National list positions could be bought.
She said the current law allowed too much room for anonymous donations, and New Zealanders deserved to know who was trying to buy influence.
Davidson called for sweeping changes, including removing anonymity for donations over $1000, capping individual donations at $35,000, banning overseas donations and increasing public money for campaigning.
But New Zealand First leader Winston Peters disagreed.
"I don't believe the taxpayer should be funding political parties to the degree that the Green Party says. The reality is, if you've got a consumer demand politically, people out there will back you."
He said New Zealand First had never taken money in exchange for political influence, but the recording told a different story for National.
"It's clear from those tapes that the National Party has a cash-for-candidates policy."
