Mr Key and his ministers also faced questions over the Auckland housing crisis and the prospect of New Zealand military involvement in the fight against Islamic State.
Green Party co-leader Russel Norman put the first of what are likely to be many questions about Mr Key's relationship with Slater, asking him how many times he had phoned or texted the blogger since 2008.
"None in my capacity as Prime Minister," Mr Key said.
Dr Norman asked whether Mr Key was claiming that when he spoke to Slater he was doing so as leader of the National Party rather than as Prime Minister.
"That has always been the claim," was Mr Key's response.
"I have never rung Cameron Slater in my capacity as Prime Minister."
However, Mr Key said he was "not 100 per cent sure" he had never used his ministerial phone to call Slater.
Mr Key's responses drew criticism from NZ First leader Winston Peters and Labour whip Chris Hipkins with Mr Peters telling Speaker David Carter he was setting a "disturbing" precedent by allowing ministers to refuse to answer questions by claiming actions were not performed in their capacity as a minister.
Dr Norman later said Mr Key was ducking accountability over his "very close" relationship with Slater.
In response to questions from Labour's Phil Goff, Mr Key did not deny he had changed his stance on involvement in the fight against Isis. "This is a rapidly evolving issue, and countries including New Zealand are having to consider the issue as it intensifies."
- Adam Bennett of NZ Herald
