A claim that records were not taken of official Stormont meetings in case they were later released to the public is nonsense, Arlene Foster has said.
The lack of notes was "shocking" and worrying but concern over Freedom of Information (FoI) requests and related political sensitivities did not influence that, the DUP leader added.
Head of the Northern Ireland Civil Service David Sterling said minute-taking lapsed after devolution and suggested the main parties in the devolved power-sharing administration in Belfast were sensitive to criticism.
Former enterprise minister Mrs Foster was in charge of planning of the botched green energy scheme in 2012 and told the Renewable Heat Incentive (RHI) public inquiry in Belfast she was unaware notes had not been taken.
She said: "I never gave a direction not to take minutes because of FoI or because I did not want anybody to see what was happening in my department."
She added it was a "nonsense suggestion about FoI" and noted policy development was exempt from the official duty of openness.
A series of fatal design flaws in the green subsidy project exposed Stormont to a huge overspend, paying out more than it cost to buy wood fuel.
This created an incentive to "burn to earn".
Mrs Foster said she did not know the overall cost of the RHI scheme when she approved it in 2012, but denied signing a "blank cheque".
She attested she did not read some technical information but it was up to others to flag up issues raised by that in their submissions to her.
"The cost control issue was not front and centre of the discussions that we were having," she said. "It was not something that was a constant source of conversation or discussion.
"I read the information given to me, I took the information at face value."
The overspending scheme ultimately prompted the collapse of devolution at Stormont.
Mr Sterling has previously told the RHI public inquiry chaired by Sir Patrick Coghlin that ministers liked to have a "safe space where they could think the unthinkable and not necessarily have it all recorded".
The DUP leader said: "I don't think there are any politicians that are not sensitive to criticism, given what I came through last year I think I am probably tougher than most.
"All politicians know that they are going to be criticised on a day and daily basis.
"None of us took decisions to avoid criticism. Politics is about not just getting elected, it is about doing something with your mandate and to deliver on what you want to deliver on."