THE state Nationals leader, Andrew Stoner, was rebuked by the Opposition Leader, Barry O'Farrell, yesterday after suggesting a federal MP should be taken outside, blindfolded and shot.

Mr Stoner's extraordinary gaffe came at a press conference as he was criticising the decision of a federal Liberal MP, Alby Schultz, to give support to independent Peter Besseling in his successful campaign to win the Port Macquarie byelection from the Nationals.

"If I had my way, I'd march him out at dawn, put a blindfold on him and shoot him," Mr Stoner said.

After being chastised by Mr O'Farrell over the telephone, he later called another press conference where he said the remark was a "joke" and apologised to anyone who was offended.

But Mr Schultz did not accept the apology yesterday, instead asking the Speaker of the House of Representatives to refer the comments to Federal Parliament's privileges committee, which can impose sanctions on people who interfere with MPs.

Mr Schultz said Mr Stoner's remarks represented "a threat against my person and therefore could be taken as an attempt to interfere with my ability to perform my duties as a member of Parliament".

He told the Herald that Mr Stoner's comments were "not fitting of a person who seeks to be the deputy premier of NSW".

Mr Schultz's involvement in the Port Macquarie byelection has been fuelling Liberal-National tensions at federal and state levels.

The federal Nationals leader, Warren Truss, has demanded the Liberal Party take disciplinary action against Mr Schultz.

Mr Stoner said he had spoken to the federal Liberal leader, Malcolm Turnbull, who had spoken with Mr Schultz about the matter.

Mr Stoner tried to play down his statement at his subsequent press conference yesterday: "If things become that serious in politics, if you can't take a joke … I'm not seriously going to march someone out and shoot them. I'm not into guns, I'm not into killing people. It's nonsense."