The Australian Government has released video footage of a navy operation to rescue asylum seekers after critics questioned official claims that children had been thrown into the sea.
Correspondents say the navy video shows people jumping overboard but is inconclusive on whether children were thrown in.
Last month's incident came after officers boarded an Indonesian ferry off the remote Christmas Island to persuade the boat's crew to return to international waters.
Australia has since late August imposed a tough policy of preventing boat people from landing on Australian territory, either turning them back into international waters or transporting them to several Pacific nations for processing.
The video reportedly shows the packed wooden ferry pitching and rolling in an ocean swell.
One frame appears to show that an adult jumping overboard had been holding a child.
I don't think [our statements have been] exaggerating or gilding the lily
Prime Minister John Howard
Vice Admiral David Shackleton said the video showed that a child had been held over the side of the ferry with "absolute intent to drop that child into the water".
He said the child was not dropped because the navy vessel HMAS Adelaide came alongside.
Prime Minister John Howard, Defence Minister Peter Reith and Immigration Minister Philip Ruddock have repeatedly asserted the asylum seekers threw children into the sea to try to force the navy to pick them up.
Mr Howard said on Thursday the claims were based on information from the Australian navy at the time.
Speaking at the National Press Club ahead of Saturday's general election, he said: "If a defence minister and an immigration minister get verbal advice from defence sources and then a prime minister gets that kind of written advice, I don't think it is exaggerating or gilding the lily to go out and say that sort thing."
Mr Howard said the advice came in a secret intelligence briefing.
Vice Admiral Shackleton said the navy's advice to ministers had been that people were being threatened with being thrown into the sea.
"I don't know what happened to the message after that." he said.
In his last major speech before the general election, Mr Howard said the choice for voters was between which side of politics can make Australia secure in what he called a turbulent, hostile environment.
The big issue, he said, was leadership. His campaign has emphasized his role in committing Australian forces to support the Americans in Afghanistan, and on his tough asylum policies.
Has stood by the claims throughout the election
Our correspondent in Sydney, Red Harrison, says the prime minister's hard line in keeping out boat loads of would-be asylum seekers has attracted strong popular support.
But it has also been criticised as cruel, inhumane and racist.
A few weeks ago, election opinion polls appeared to show Mr Howard would romp home.
But analysts say opposition Labor Party leader Kim Beazley has recovered by concentrating on domestic issues and by outshining the prime minister in the campaign's only televised leadership debate last month.
His campaign has promised to create job, cut taxes, improve public health services and increase spending on education to make Australia, what Mr Beazley calls, a knowledge nation.