PEOPLE smugglers may have deliberately capsized two boats between Java and Christmas Island last month, killing 94 people, military sources suspect.
As another rickety vessel carrying 39 people was intercepted on Sunday night, authorities are investigating whether crews scuttled the fishing craft in a bid to hasten rescue efforts.
Military sources strongly suspect the first vessel to capsize, on June 21, was deliberately turned over so survivors could cling to the upturned hull.
The second vessel foundered on June 27 after taking on water in very calm seas, and two of its four crew members were removed by a second boat.
"Before she foundered we received a distress call saying, 'We are capsizing'," a defence source said.
A navy source said it was highly unusual for two boats to turn over in the same area within a few days of each other: "The sea at the time of both incidents was not rough."
The Gillard government is set to announce a whole-of-government review of the response by Australian agencies - including Border Protection Command, Customs, Defence and Immigration - into the twin tragedies.
Australian Federal Police officers and the West Australian Coroner have begun interviewing survivors about tactics used by the smugglers.
The first boat got into trouble about 100km south of Java and the second about 20km northwest of that position.
Ninety people died in the first disaster and four in the second, despite the best efforts of the navy patrol boats HMAS Wollongong, Larrakia and Maitland, the survey ship HMAS Leeuwin and merchant vessels.
A government source said, while there was no direct evidence the boats had been deliberately capsized, statements from witnesses - including passengers, rescuers, and navy, RAAF and Border Protection Command observers - had raised alarm bells.
"This is a dramatic escalation and it is suspicious," a government source said.
Up to 300 refugees a week arrive at Jakarta international airport on one-way tickets en route to people smuggling vessels bound for Australia.
As the boat people continue to pour in, the navy is bracing for sailors suffering from psychological damage after pulling dozens of dead bodies and hurt people from the sea.