Acting Prime Minister Gerry Brownlee has refused to answer any questions in Parliament on the outcome of the teapot tape investigation.
Mr Brownlee told MPs there is no ministerial responsibility in the matter.
During question time, opposition MPs asked if the Prime Minister was embarrassed by the police decision not to lay charges over the secret recording of the pre-election conversation between John Key and ACT candidate for Epsom, John Banks.
Mr Brownlee told MPs there is no ministerial responsibility in the matter because Mr Key was involved in the investigation as the leader of the National Party.
But Labour MP Trevor Mallard told Parliament Mr Key made comments on Monday on the police decision as the Prime Minister.
New Zealand First MP Denis O'Rourke also questioned the timing of the decision, saying it was convenient for the Prime Minister to be out of the country when it was released.
Mr Key is in Korea for a nuclear summit.