Last night, Sir Bruce, who was GCSB director from 2006 to 2011, said reports suggested a full selection process was not run and that was consistent with what he had heard anecdotally.
Sir Bruce said he was aware of one candidate who was shortlisted but "at the 11th hour was told don't come to an interview, they've already selected a candidate".
The man, whom he'd known for 25 years and who had an appropriate military or intelligence background, was eminently suitable as a candidate, he told TV3's Campbell Live.
"The State Services Commissioner is very much entrusted in running an apolitical selection process. From what I hear it appears that may not have happened and if that didn't happen I find that quite disturbing."
State Services Commissioner Iain Rennie last night said he "strongly refuted" Sir Bruce's claim and said he was "outraged that there has been baseless attacks on the credibility of Mr Fletcher's appointment".
He had advised Mr Key that given the requirements of the job, the candidates on the shortlist "should not be considered further" and a further search was needed.
"For this position ... it was not essential to have a military or intelligence background. GCSB is a civilian agency, and the position description emphasised the importance of leadership and change-management expertise in this role."
Yesterday, Mr Key - who had previously deflected questions about his involvement by saying the State Services Commission was responsible for the appointment - acknowledged phoning Mr Fletcher about the job.
He said he had not mentioned the phone call earlier because "I'd forgotten that at that particular time".
But the phone call "wouldn't make any difference" to his answers about his role as he did not regard it as part of the appointment process.
Just a week ago, Mr Key told reporters he only "vaguely" knew Mr Fletcher because of the friendship between their mothers and he could not recall particular occasions when he met up with him in recent years.
It later emerged the two men met over breakfast or lunch on at least three occasions in recent years.
His relationship with Mr Fletcher has been under scrutiny because, as GCSB director, Mr Fletcher reports to him on security matters which will have included the bureau's illegal surveillance of controversial internet tycoon Kim Dotcom.
Labour Party deputy leader Grant Robertson said the call to Mr Fletcher was "very much part of the appointment process and it in my view made it a far less transparent process than New Zealanders would expect".
What role did he have in Mr Fletcher's appointment?
Last week
"Only that the State Services Commissioner came to me with a recommendation."
Yesterday
"I rang him and said look I think you might be interested, if you are interested in finding out about the job you should go and speak to Maarten Wevers who is the head of DPMC and see if that job is of interest to you."
Key's memory lapses
* Forgot how many Tranz Rail shares he owned.
* Unsure if and when he was briefed by GCSB on Kim Dotcom.
* Forgot how he voted on drinking age.
* Could not recall whether he was for or against the 1981 Springbok Tour.
* Could not remember who was aboard mystery CIA jet parked at Wellington airport.
* Forgot he phoned future director of GCSB urging him to apply for the job.
