A Canberra public servant accused of leaking confidential information about the Iraq war has lodged an application in the High Court to have his legal costs paid by the Department of Foreign Affairs and Trade (DFAT).

The department sacked employee Trent Smith and alleged he sent an email in 2002 to the then federal Labor opposition in breach of the public service code of conduct.

He was also accused of leaking a confidential document that showed Australia committed to the Iraq war long before the public knew.

The Australian Industrial Relations Commission (AIRC) found the dismissal to be "harsh, unjust and unfair" and ordered he be reinstated.

The AIRC described DFAT's case as lacking in truth and credibility.

Mr Smith's lawyer James King says his client is now struggling to pay the $350,000 he spent defending the matter.

"I just see the situation as rather unfortunate," he said.

"Essentially a hard working public servant who simply wanted to return to work is faced with quite crippling financial consequences.

"It really shows that unsubstantiated allegations can be exceptionally damaging in that a public servant on his own needs to defend them and incur those costs."

Mr King says the Attorney-General, Minister for Finance and Minister for Foreign Affairs should now review the matter and correct the error that has been made.

"Basically in the interests of justice, to say that Mr Smith's legal costs and costs associated in defending the matter should be reimbursed in full," he said.

"The Government can do that by way of an ex gratia payment if they chose to do so."

In a statement DFAT says it has met its obligations by reinstating Trent Smith and points out that the AIRC dismissed Mr Smith's application for costs.