Abbott goes for the immigration card in his play to Aussie voters

AUSTRALIAN opposition leader Tony Abbott has pledged tougher prison sentences for people-smugglers as he formally launched his campaign to unseat the Labour government in the 21 August election.

Abbott also promised a united team if he wins office - pointing to dissension within Labour since Prime Minister Julia Gillard replaced her predecessor in a party coup in June.

Illegal immigration is shaping up as a decisive issue in what is likely to be a close election, with opinion polls showing that voters in marginal seats are concerned that Canberra is not doing enough to turn back boatloads of asylum seekers.

Surveys show Abbott's conservatives have a real chance of defeating Gillard, with the government's campaign hurt by tensions over the removal of former prime minister Kevin Rudd.

In his main new policy in the campaign speech yesterday, Abbott said people-smugglers who repeatedly offended would go to jail for 10 years or more - sentences more akin to rape and manslaughter.

"We are determined to send a strong message to people smugglers that their cruel and callous trade in human cargo must stop," Abbott told an auditorium packed with cheering Liberal-National Party coalition supporters, under the banner "Stand up for Australia, stand up for real action".

Gillard dismissed suggestions that the government had failed to take action against people smuggling. "We've got mandatory jail sentences in the current legislation. We have had a crackdown," she told Australian television.

Border protection laws introduced this year set a penalty of up to 20 years' jail and up to 10 years for assisting smugglers.

Abbott also promised to set up a carbon-emissions reduction fund in his first three months to combat climate change. He opposes the government's plan for a carbon-trading scheme.

If he wins, Abbott said Australia would meet targets to cut greenhouse emissions by five per cent by 2020, but through tree planting and other moves - not through a carbon tax or trading.

"What we will never do, though, is damage our economy with futile environmental gestures," he said.

The Greens, who are likely to hold the balance of power in the upper house Senate after the election, yesterday proposed a long-term 100 per cent renewable energy target, and said they would push for AU$5 billion in green loans to promote big clean energy projects.

Abbott also promised to kill off Labour's proposed 30 per cent mining tax on the first day of a conservative government, produce a national economic blueprint within his first month, and to outline tax reforms within his first 12 months.