"As I said at the time these allegations were first raised I have complete confidence in defence's intelligence and security community," he told a Senate estimates hearing on Wednesday.

"They are professionally, personally and morally committed to Australia's security and they work tirelessly to work and protect Australia's national interest."

Ian Carnell, the director-general of intelligence and security, conducted an investigation following newspaper reports in March that defence intelligence and security staff had been investigating Mr Fitzgibbon's relationship with Chinese businesswoman Helen Liu.

Last week, defence released an internal inquiry clearing the department of any wrongdoing.

In his report, Mr Carnell said he found "no evidence of indication which might raise suspicion that the allegations concerning DSD personnel are correct".

The allegations had claimed that staff from the Defence Signals Directorate (DSD) had accessed the minister's computer as part of a covert investigation into Mr Fitzgibbon.

As part of his investigation, Mr Carnell's office conducted a forensic examination of information technology systems but could "not identify any unauthorised access or attempts at unauthorised access".

He noted he had sent an open letter to all defence staff to see if any held any relevant information, but the email to the department only generated one response of little consequence.

Mr Carnell's main findings were:

* There was no evidence or indication which raised suspicion of an official or legally-sanctioned investigation of Mr Fitzgibbon by DSD.

* There was no evidence or indication to raise suspicion that any DSD officer were part of an unofficial investigation.

* DSD had not accessed any of the personal information claimed in media reports as part of its information security role or through other legitimate activities.