Australian election campaign's final debate focuses on national security, climate change

CANBERRA - Leaders of Australia's two biggest political parties have gone head-to-head in their final debate before the general election on May 18.

Prime Minister and Liberal-National party coalition (LNP) leader Scott Morrison and Australian Labor Party (ALP) leader Bill Shorten clashed over national security and climate policy on Wednesday night.

Shorten confirmed that his party would release the full costings of its proposed policies, including its ambitious emissions reduction and renewable energy targets, on Friday.

The unknown cost of the pledge to reduce carbon emissions by 45 percent from 2005 levels by 2030 has been a significant problem for Labor on the campaign trail, with the LNP attacking the party as being fiscally reckless at every opportunity.

"It's been now well over three weeks during the course of this election campaign, it's about 10 days or so that everyone will go to the polls. And we still haven't heard what the cost to Australians is," Morrison said.

While Labor's campaign has focused strongly on healthcare, education and infrastructure, the party has been reluctant to engage in a national security debate with the government.

However, asked on Wednesday night about his credentials on the issue, Shorten fired back at the LNP's national security record.

"They've had five defence ministers in six years, that's not exactly providing certainty in national security, is it."

The first two debates had undecided voters declare a winner on the night but the third, hosted by the Australian Broadcasting Corporation (ABC) and the National Press Club, did not follow that format.