YesCymru said a majority of its board of directors made the decision to ensure its finances remained "in a healthy position".

In a statement, the campaign group's chair, Barry Parkin, said it had a "responsibility to ensure that membership money is spent wisely".

Mr Parkin said it was "not an easy decision to make" but added that Gwern Gwynfil had been aware of discussions surrounding the future of the position.

"The phrase 'sacked', which I have heard used about the board's decision, implies or gives the impression that the CEO was dismissed for misconduct or inappropriate behaviour. There is nothing further from the truth," Mr Parkin said.

YesCymru confirmed it would be honouring any notice period within the chief executive's contract but Mr Parkin said he was "not at liberty to reveal those details".

Mr Parkin claimed there were elements trying to "undermine the legitimate majority decisions" of the board.

"Those elements will not succeed in undermining our focus, which remains to support our grassroots members, the local groups, and campaigns to continue to stimulate the growth we have seen recently in the support for Welsh independence," he said.

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Mr Gwynfil told Sky News he had been "inundated with messages of support" in recent days.

"If I could take an opportunity to thank all of those who have done so, it really does feel as though I've been buoyed up by a sea of love three or four days before Christmas and that has been incredibly supportive and useful for me personally," he said.

"Ultimately, the cause of independence is far bigger than any individual or small group of individuals and YesCymru is, has been, and will continue to be an absolutely key part of that campaign."