Rob Campbell's behaviour is being described as "a remarkable act of self-immolation".

The former Te Whatu Ora chair has been fired for taking issue with National's Three Waters policy online and breaching the code of political neutrality for public servants.

A decision to sack him from his role as chair of the Environmental Protection Authority is expected today.

Former Cabinet Minister turned political commentator Peter Dunne told Mike Hosking for Campbell to argue he was speaking out as a private citizen, is either deliberately naïve or mischievous.

Dunne says he's an experienced director who must have known he was playing with fire when he published those comments on social media.

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