Former prime minister Bob Hawke has urged the country's leaders to speak frankly and directly with the public following the twin tragedies of the Sydney siege and Cairns stabbings.

The 85-year-old was at the opening day of the Woodford Folk Festival in Queensland's Sunshine Coast hinterland, where he is a familiar face most years either on stage or in the crowds.

This year, more than 100,000 people are expected to attend the annual festival over six days.

The event is Australia's largest annual gathering of artists and musicians and runs until New Year's Day.

Mr Hawke acknowledged it had been a tough end of the year, with the Sydney Siege, which saw the deaths of two hostages, followed less than a week later by a mass murder in Cairns, in which eight children under 14 were killed.

"There's a sort of tautness in the community as a result of all those strains and tragedies," Mr Hawke said.

"For people to be able to come together and relax in such a beautiful atmosphere is, I think, very appropriate.

"Hopefully it will give us a good start to what I hope will be a much better year."

Mr Hawke said leaders have to speak "frankly and directly" with the public.

"They have to say there is a real threat from extremism in the world and let it be remembered, it's not just Islamic extremism, although that is, of course, the most obvious in a sense at the present time," he said.

"I said it to some of my Jewish friends when talking about these things ... it wasn't a Muslim extremist that killed the Israeli prime minister, it was a Jewish extremist."

"And it was the extremists of the Christian right in the United State which nurtured the ambitions of George Bush Jr to undertake that enormously counterproductive war in Iraq.

"So I think it's up to our leaders to stress that the major religions of the world are basically good institutions.

"They espouse fine ideals and we should all attempt, even if we're not believers, to live up to the principals of the great religions and not to identity the extremists as characterising the realities of those religions."

Mr Hawke will be interviewed on stage during the Woodford Folk Festival but said he has no idea what the topic will be.

"Anything could happen," he said.