The proceeds will benefit Cooper, as well as The Kerry Cancer Support Group and Our Lady’s Children’s Hospital, with an unspecified split at Cooper's discretion.

The Kerry legend said Duffy had "no issue with it whatsoever", but the Director General has contradicted this on RTÉ Radio 1's Today with Sean O'Rourke programme.

"That is not quite right. What I said to Colm when he came to see me, and I said it very clearly, was that I had a concern here about how this might impact on your amateur status and on our rules," said Duffy, who yesterday revealed he will retire at the end of March 2018.

"We looked at the rules, got our legal advisors to look at them. They came back and said 'he's not breaking any rules'.

"I went back to Colm and said, 'no, you're not breaking the rules. If you go ahead with this you will not be suspended and no charge will be levelled against you'.

"But I said, 'Are you sure you're doing the right thing here?'

"I told him the GAA would not be supporting it and we’re not supporting it."

Duffy explained a testimonial is seen as different to any other form of profiting from a book of punditry as it takes from the pool of money available to clubs and counties.

"If you do an autobiography or punditry, you're not taking funds that could go to the GAA. If you're holding a major dinner you're going to the same people to support the dinner or testimonial as you would to support a club event.

"That's the big concern I would have. Plus the fact that it is against the ethos of the GAA to run a dinner where the individual benefits. We don't do that."

The GAA can't prevent future testimonials under current rules, but have sought legal advice and vowed to examine the issue.

"I’m very clear on this, our organisation does not want testimonials," said Duffy.

"It’s the message I have got very clearly over the last few weeks. It's nothing to do with Colm Cooper - he's just the first. We are an amateur organisation, we don’t reward our players financially.

"In other situations players may benefit ‘under the counter’ and that’s something we can’t deal with now.

"This is a public thing. It’s there, we have to express our view on it. Our view is we are not going to support it.

"At a management committee meeting last Friday week, we decided to take some form of legal advice on it. It won’t affect this testimonial, but it may have an impact in the future."

On his own departure, Duffy said: "I personally feel that ten years is long enough in the role and that whatever you can do for the organisation, if you haven't done it by now it's not likely you are going to do it in the future.

"I think it's a good time to go, it's good for me and it's good for the GAA."