Sydney broadcaster Alan Jones says his remark that Prime Minister Julia Gillard should be thrown out to sea in a chaff bag may have been better left unsaid.

After an address to the National Press Club, Jones was asked by a journalist whether such comments diminish respect for the office of the Prime Minister and if he regrets them.

Jones says chucking something in a chaff bag is an old-fashioned farming analogy.

"If that is misunderstood and if that in any way diminished the respect that people have for the office, then certainly it was a comment better left unsaid," he said.

"Sometimes in the heat of what you're doing - you're going at a 100 miles per hour - these things are said. We don't always say things that are right, we don't always say things that are fair, [but] we should try to," he said.

Jones also apologised for making allegations that police stopped anti-carbon tax protesters at the NSW-ACT border from attending a rally in August.

He made the allegations at the so-called convoy of no confidence rally in Canberra.

ACT police rejected the claim, saying officers did not stop any vehicles.

"It would do me no harm whatever to apologise to anyone who might have been offended by the inference that the police weren't doing their job," he said.

"I think the police were doing their job, but these people were stopped - now, what was the point of that, I don't know."

Jones also used the press club address to call on Queensland Premier Anna Bligh and Treasurer Andrew Fraser to quit because he says they support mining over agriculture.

He was particularly critical of Xstrata's open-cut coal mine at Wandoan in southern Queensland which has the potential to become the biggest open-cut coal mine in the southern hemisphere.

Jones says the Queensland Government is putting the nation's ability to feed itself at risk.

"This is a brutal thing to say, but Anna Bligh and Andrew Fraser should be asked to stand down immediately," he said.

"If any general in war deliberately did to their troops what the Premier and the Treasurer in Queensland have done to their people, they would be court martialled."