"I have worked under this Government for four years and in that time I have never received pressure from ministers to act in a particular way and the PM in particular has always been particularly scrupulous."
Mr Rennie said that in hindsight, it would have been better if he had contacted Mr Fletcher himself because of the perception issues created by Mr Key contacting him.
However, there was no legal, or moral or ethical bar to prevent ministers contacting potential candidates themselves.
Mr Rennie said the role the Prime Minister had taken in Mr Fletcher's appointment was not atypical of the way such appointments were made.
He said unlike core public service roles such as the Secretary of the Treasury, the head of the GCSB and others such as the Chief of Defence Force, the Police Commissioner, director of NZSIS were all positions appointed by ministers and who serve at the pleasure of a minister.
"How ministers involved themselves in the process varies. In my time some ministers have been at arms' length, others are more involved."
He said one minister had gone so far as to interview the short listed candidates in such a situation.
For other public service roles, the minister was not consulted in the same way and Rennie himself chose the successful applicant.
Mr Rennie also said he was "disappointed" by comments made by former GCSB head Sir Bruce Ferguson yesterday, saying Ferguson had not understood the process properly.
He said Ferguson's claim that other short-listed candidates were dispatched at very late notice in favour of Fletcher was not true. It was usual practice to discuss the short list presented by a recruitment consultant to the minister to discuss whether it should stand, be added to or deleted from.
He said all short listed candidates knew there was a chance they might not make the interview process and that the Prime Minister would have some input.
"Those who were shortlisted were told the PM had considered their applications and they were declined at that point."
He had offered advice to the Prime Minister on that short list, saying he did not believe they were best placed to take the role given the changes that were needed at GCSB at the time.
It is the first time Mr Rennie has personally fronted up since Mr Key admitted he personally rang Mr Fletcher to suggest he apply for the role, although Mr Rennie has sent out written statements.
He rejected claims that the panel which interviewed Mr Fletcher might have been influenced by Mr Key's suggestion of Mr Fletcher as a candidate.
"The suggestion [the three people on the panel] are somehow going to be swayed by the Prime Minister making a phone call to suggest someone enter the process is frankly quite bizarre."
The panel which interviewed Mr Fletcher was made up of Sir Maarten Wevers (head of the Department of the Prime Minister and Cabinet), Secretary of Defence John McKinnon and State Services deputy commissioner Helene Quilter, and Mr Rennie himself.
He said those on the panel were accustomed to applying a "professional and objective view" in such circumstances when ministers were involved.
Mr Key stood by his decision to contact Mr Fletcher himself and said he had also directly approached other people about potential positions.
Asked today whether in hindsight he regretted it and believed he should have left it to Mr Rennie, Mr Key said "no''.
"I think that process has been well covered. There was a very thorough process when he was interviewed and all that. It was very robust. The State Services Commissioner made that quite clear as well and I think that is the appropriate way.''
Mr Key also rejected comments by former GCSB director Bruce Ferguson that it was advisable to have someone with military experience leading the agency - and took a swipe at Mr Ferguson's own tenure of the agency.
He said a review of the agency by Rebecca Kitteridge would show other skills were required.
"When that review is released in a couple of weeks, it will identify quite major issues that need to be rectified. They were issues that were there under Mr Ferguson and others. That shows you that just having a military background hasn't delivered the robustness of that organisation that New Zealanders would expect.''
He said that report would result in changes in the oversight of the GCSB as well as likely changes to the role of the Inspector General of Intelligence and Security, which is a watchdog over the actions of the agency.
Labour Deputy Leader Grant Robertson has confirmed he will file a complaint to Parliament's Speaker that Mr Key misled the House by not fully disclosing his role in Mr Fletcher's appointment in response to questions.
Green Party Co-leader Russel Norman this afternoon said he would ask Parliament's Intelligence and Security Committee - which is comprised of party leaders - to investigate Mr Fletcher's appointment.
"Serious questions about the appointment of New Zealand's top spy need to be answered and that's why I am seeking this open inquiry'', Dr Norman said.
"John Key did not tell the whole truth about the appointment process when he said in Parliament the State Services Commissioner made the decision. Mr Key failed to mention that it was Mr Key who had rung Mr Fletcher to suggest that he apply for the job.
"The Prime Minister should stand aside from the vote on whether to allow the inquiry to go ahead if he is to have any credibility on this issue.''
