Government analysts would be "encouraged" to make submissions, said David Jull, chairman of the joint parliamentary committee which will investigate Australia's pre-war intelligence on Iraq.

The investigation does not have the jurisdiction to question the Office of National Assessments (ONA) and the Defence Intelligence Organisation (DIO), which assessed raw intelligence gathered from domestic and foreign sources.

It was based on those assessments that conservative Prime Minister John Howard decided to support the United States and Britain in the military invasion of Iraq.

Howard was forced by the opposition-dominated Senate last week to open an inquiry similar to those already launched by the US Congress and British parliament into whether evidence of Baghdad's weapons of mass destruction was doctored.

He has defended his decision to join the invasion of Iraq despite widespread domestic opposition as necessary to prevent the spread of chemical, biological and possibly nuclear weapons allegedly held by Iraq.

But since US-led forces toppled Saddam Hussein's regime in April, no stockpiles of banned weapons have been found.

Jull said he was hopeful that the analysts would cooperate with the investigation.

"We will be advertising on July 5 for public submissions...they may come from all manner of people including weapons inspectors and we would hope that we would get some fairly good cooperation from other agencies like the ONA and DIO and maybe in a voluntary sense they may appear before our committeee," Jull told commercial television.

Labor opposition foreign affairs spokesman Kevin Rudd said it was important to establish whether the analysis conducted by the agencies was "well-founded and sound".

But Jull said that the inquiry would still be able to do its job without their submissions.

"But if they don't, I don't think that really matters because they really are the analysts and it will be the information that is being fed from other agencies to those agencies that will be very much under scrutiny," he said.

"It will be good if we can have them but if we don't I still think we very much have a capacity to be able to nail things down a bit."

Jull said the inquiry, which begins next month, should report its findings by early December.

He conceded that many of the hearings would not be open to the public due to the nature of the evidence, an issue much criticised by minor opposition parties.

"We will have public hearings and the whole thing will be open to the scrutiny of the press," Jull said.

WAR.WIRE