Regrets, I've had a few: Jones

He also expressed regret for saying Prime Minister Julia Gillard should be put in a chaff bag and hoisted out to sea.

Mr Jones, who was addressing the National Press Club on the issue of national food safety and the ''invasion'' of Australia by mining and coal seam gas companies, said he did not mean to cause offence to police or the office of Prime Minister.

In August, Mr Jones addressed a rally outside Parliament House in which he alleged the Australian Federal Police was stopping trucks at the NSW border to prevent them from taking part in the Convoy of No Confidence. He described it as ''the most disgraceful thing that's ever been done to democracy''.

But both the protest organiser Mick Pattel and ACT Police strenuously denied any trucks were stopped - instead explaining that about 60 trucks had pulled over at the border so the rest of the convoy could catch up.

Mr Jones said yesterday he would never want to reflect badly on police officers who ''have an impossibly difficult job to do at the best of times''.

While he maintained the trucks had been "stopped at the border", he added, "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 there job."

Similarly, he said his statements about the Prime Minister would have been ''better left unsaid''.

He noted Ms Gillard had been 12 minutes late for a radio interview, and this had been very stressful on live radio. But he later realised he had been too hard on her and composed an email apology.

When it bounced from an old email address, he had rung her office to ask for a new address but had been referred on to a staffer and did not send the email for fear it would be made public.

"In the cold light of reflection after the program I sat down and thought I think that was a bit much really ...You have to be very respectful of the office and on those occasions I most probably didn't meet the standards of those who listen to the program but I assure you we always try to do that - sometimes we fail."

Mr Jones, in his trademark style, delivered a passionate and lengthy oration at the Press Club in which he warned that mining and coal seam gas extraction was out of control in Queensland and NSW.

He said some of Australia's prime farming land risked being turned into industrial wastelands with state and Commonwealth governments putting at risk public health, water quality and the nation's ability to feed itself.

Mr Jones said scientists were unsure about the safety of fracking techniques - the injection of chemicals, water and sand at high pressures to crack rock and release gas - used by mining companies to find coal seam gas.

He believed there were well-founded fears these fracking chemicals would poison underground water, contaminate good agricultural soil and cause serious health problems.

He said ''broke'' governments were putting mining royalties above concerns about health and the environment, and were falling prey to a bevy of lobbyists employed by the industry.

Mr Jones warned the mining companies were unscrupulous in their approach, and "farmers are being invaded".

Many were "bullied" into selling their land and forced to sign confidentiality agreements.

In the meantime, Australia was losing some of its best agricultural land to foreign mining interests when it needed to consider future food security issues.

"Where is our food security if we either sell our best land to foreign interests, or allow mining interests to plunder it?" he asked.

Mr Jones warned farmers were starting to mobilise against mining and coal seam gas companies through the "Lock the Gate" campaign and a national backlash was growing.

He also called for a Commonwealth Department of Food Security, to put mining companies under adequate scrutiny and to ensure the safety and ongoing viability of Australian agriculture.