'FOREARMED IS FOREWARNED': John Key is changing his style when it comes to answering questions.

Prime Minister John Key says he will no longer answer questions about his actions without warning, following controversy over his role in the appointment of spy boss Ian Fletcher.

During an interview on Radio Live, Key described those reporting on the story as ''knuckle heads'' and said he would change his approach to answering questions both in Parliament and to the media.

Key has faced accusations of ''brain fade'' after recalling that he called Fletcher, a childhood friend, to ask if he was interested in the role of director-general of GCSB.

In Parliament on March 27, when asked of his role in Fletcher's appointment, Key said: ''His appointment was made by the State Services Commissioner''.

He later said that he could not remember any particular meetings with Fletcher since their school days.

''I am sure I may well have done so.''

Today Key said his answer was "absolutely correct" on the appointment but he accepted that he had not recalled the phone call seeking Fletcher's interest in the job and took responsibility for the lapse.

Denying accusations that he had lied by omission, he said he had only had ''15 seconds, with no warning, on a process that happened 18 months ago'' and he should have taken time to research the answer.

''What I should have done, and what I will be doing in the future, is saying, well, the member needs to put that down to me in writing, and I'll be doing that to the journalists as well,'' Key said.

''Cos if you want perfection of everything I have done, two, three, four, five years ago, I will get you all that information for you, but I'll get you the whole lot and give it to you,'' he said.

The attacks by Labour were ''low rent politics'', which he accepted was ''the game'' but it would prompt a change in his style.

''But forearmed is forewarned. I'm changing too.''

Key said his contact with Fletcher had been a ''nothing phone call'' of less than two minutes and that he had spent more time thinking about the other person he had in mind for the job, who he has declined to name.