The Prime Minister has been criticised for writing his only letter of apology this year to the right-wing blogger Cameron Slater.
The Labour Party said there had been more important things John Key could have apologised for.
In reply to a written question from Labour, the Prime Minister said he had written one letter of apology over the past 12 months.
His office has confirmed that was to Mr Slater for releasing a private email that led to the resignation of Justice Minister Judith Collins.
Labour Party leader Andrew Little said Mr Key and Mr Slater were good, close friends.
"I can't imagine there was a great deal of hurt and humiliation involved in whatever it was that John Key felt he needed to apologise for."
Mr Little said Mr Key should have apologised to the complainants in the Roger Sutton case after a botched handling by the State Services Commissioner, or to those involved in other cases where there had been failures at the senior levels of government.
"It is appropriate for the Prime Minister, not because he has personally done anything wrong, but because he represents the senior levels of government and ought to be able to show contrition."
Mr Little said the Prime Minister was showing his arrogance in thinking his government could do no wrong.