The Australian government Saturday blasted as "highly dangerous" plans by the conservative opposition to order the navy to turn around asylum-seeker boats and return them to Indonesia if it gains power.

Though they come in relatively small numbers by global standards, asylum-seekers are a hot political issue in Australia and dominated national elections in 2010 due to a surge of almost 7,000 arrivals.

Most arrive via Indonesia where they link up with people-smugglers for the sometimes deadly sea voyage to Australia.

If elected prime minister, opposition leader Tony Abbott said he would tell Jakarta that Australia would impose tougher policies to secure its borders, which could have implications for bilateral relations.

"This is a test of wills and Australia has lost," Abbott was quoted as saying by The Australian.

"What counts is what the Australian government does, not what it says.

"It is time for Australia to adopt turning the boats back as its core policy."

His comments come after an overloaded vessel, carrying about 250 mostly Iranian and Afghan asylum seekers heading to Australia, sank off Indonesia's eastern Java last month, killing all but 47 people on board.

Canberra has tried to deter boatpeople by setting up offshore processing, intending to send up to 800 asylum-seekers arriving in Australia by boat to Malaysia, in return for accepting 4,000 of Kuala Lumpur's registered refugees.

But the proposal was scotched in August by the High Court, which said Australia could not guarantee their safety with Malaysia a non-signatory to UN refugee conventions.

It placed all offshore processing in doubt, and Abbott's party has so far effectively blocked new legislation to allow it.

The Australian said Abbott's proposal would involve an increase in the number of naval vessels to force the boats back.

This would include having the capacity to remove asylum-seekers from deliberately sabotaged boats before repairing the vessels to enable the boatpeople to be returned to Indonesia.

Immigration Minister Chris Bowen called the plans "not only impractical but highly dangerous".

"I don't think treating people in a brutal way on the high seas and risking the lives of them and Australian personnel is the way to go," he said.

"He (Abbott) says he's going to turn them back to Indonesia, indeed, he's going to put them on Australian naval ships and take them back to Indonesia.

"One little problem with that: Indonesia has said repeatedly, 'Forget it. We're not going to take them.'"

Labor Prime Minister Julia Gillard currently rules a national coalition government which has a slender majority in Canberra with elections due in 2013.