An adviser to the Australian government is claiming she was sacked because she refused to exaggerate the threat posed by Saddam Hussein.
2,000 Australian soldiers were sent to Iraq
Jane Errey, 43, has lodged an unfair and unlawful dismissal suit against the federal government.
She said: "I felt that a lie was being perpetuated, and as a public servant I was contributing to that lie."
The defence department maintains she was dismissed earlier this month for failing to turn up for work.
Ms Errey, who had worked for the department for nine years, was an adviser to former chief defence scientist Ian Chessell.
Access to secrets
She wrote briefings for Defence Minister Robert Hill, and had access to secret intelligence on Iraq's weapon capabilities.
When she was asked to write a briefing in March last year that she believed exaggerated details of Saddam Hussein's weapons capabilities, she says, she refused and took annual leave the next day.
"The Australian public was being told one thing, and that was the basis for Australia to go to war, and as it is becoming blatantly obvious... that simply wasn't the case," she said at the Australian Industrial Relations Commission.
If she wins her case, the court can order the government to pay compensation.
The Australian government sent 2,000 troops to join the US-led war in Iraq, largely on the basis of intelligence reports.
It has set up an inquiry into Australia's pre-war intelligence, following concerns, echoed in the US and UK, that the information may have been unreliable.
The defence department said Ms Errey was ordered to return to work by 31 March, having been absent without an adequate explanation since December.
Ms Errey claimed she had asked to go on unpaid leave because she felt "professionally compromised" by the stance the government was taking.
She says if she regains her job, she will stay on leave until Australia changes its position over Iraq.