Green MP Steffan Browning is facing disciplinary action from within his party over a controversial social media post about outgoing former Prime Minister John Key.

It featured a photo of a glass of red-coloured water on Mr Browning's desk in the debating chamber on Wednesday, taken during Mr Key's valedictory speech.

Mr Browning blasted Mr Key's "disgusting legacy", referring to claims made in Nicky Hager and Jon Stephenson's new book that he authorised two failed raids in Afghanistan that killed six civilians.



"Thought John Key might like a little more blood for his valedictory speech, the day that we get confirmation of the raid he approved was responsible for innocent civilian deaths," the Facebook post said.

Mr Browning has since deleted the post, following a phone call from Greens co-leader James Shaw on Wednesday night.

"It is a breach of the code of conduct we have for Green MPs, because one of the things we say is that we don't engage in personal attacks," Mr Shaw told Newshub.