The Australian Broadcasting Corporation on Saturday called a clear win for the Tony Abbott-led conservative opposition over Prime Minister Kevin Rudd's Labor in national polls.

With nearly 21 percent of the vote counted, the ABC predicted Abbott's Liberal/National coalition will win 90 seats in the 150-seat lower House of Representatives. It forecast Labor will take 58.

"At this stage I'm seeing consistently Labor behind and losing seats," the state broadcaster's election analyst Antony Green said.

"The coalition is on a pretty secure 74 seats already. On that basis they're going to get a majority. I think we can say the government has been defeated."

Several senior Labor figures have already conceded Abbott will win, led by Defence Minister Stephen Smith.

"The government will be defeated tonight," he told ABC.