The National Party has labelled Environment Ministry chief executive Hugh Logan a scapegoat after he resigned this morning.
State services spokesman Gerry Brownlee said the ministry had become politicised and minister David Parker and State Services Commissioner Mark Prebble had questions to answer.
In a statement this morning Mr Logan said he will leave the job on February 1.
"We have had a rough few months. There have been mistakes made in managing employment situations and communications with the Minister. Where these have occurred, I have been prepared to take the responsibility, apologise, and put things right," Mr Logan said.
The Ministry for the Environment has been at the centre of a series of political scandals in recent months, including the removal of former communications staffer Madeleine Setchell because her partner was the senior press secretary to National Party leader John Key.
Mr Logan has been forced to apologise three times in the past month for various errors made by the Ministry, twice relating to advice given to Environment Minister Trevor Mallard.
Mr Brownlee said if Mr Logan's resignation is due to the advice he gave Mr Mallard, he would not be resigning three hours before a report from the State Services Commission is due out.
"We note that Hugh Logan was not at the Ministry of Environment at the time (Labour Party activist) Clare Curran was employed," Mr Brownlee said.
The fast-tracking of communications contractor and would-be Labour MP Clare Curran was recommended by Climate Change Minister David Parker, and led to whistle blower Erin Leigh being attacked in Parliament by Trevor Mallard after receiving advice from Mr Logan.
Mr Logan later apologised for the affair. He said the information was not intended to reflect on Ms Leigh's performance.
But he said recent events had created a situation where the Ministry needed a fresh start if it was to be able to focus effectively on the critical changes needed in environmental management in New Zealand.
A State Services Commission report into concerns about politicisation of the ministry's communications is due to be released at 2pm today.
Brownlee said he looked forward to the report being released and is anticipating Mr Parker and Mr Prebble will have further questions to answer.
However, the earliest the opposition will be able to ask those questions will be February, with Parliament rising until next year.
"It's a disgrace that the report has been held back until after the house was lifted," Mr Brownlee said.
Mr Logan will receive three months' pay in lieu of notice according to his contract, though he leaves in just over a month.
He may continue to carry out research work for the Ministry - at one quarter of his current salary.
An acting Chief Executive will be announced in the New Year and a search for Mr Logan's successor will begin early in 2008.
A statement issued by the Ministry said that while Mr Logan did not accept all the criticisms that had been made, the bigger issue was "not to distract the Ministry from the really important job that has to be done".