The case is part of legal action under way at Fair Work Australia, although details of proceedings are not being made public.

While reports in the past year have detailed links between AFP officers and organised crime syndicates - mainly in the form of outlaw bikie gangs, which have also infiltrated the state police in Victoria - leaks from the federal police agency to a foreign entity have not been uncovered until now.

Documents detailing the corruption investigation refer to an incident in which a man deceptively impersonated another AFP employee who was a sworn police officer.

The sacked man was not a sworn police officer himself and was described by the AFP

as an appointee, meaning he could have been an AFP protective services officer, which guard Commonwealth government and Australian Defence Force buildings, or a public servant, consultant or independent contractor used by the AFP.

The AFP's professional standards investigation found he never disclosed his relationship with the foreign government representative.

The man also misused his AFP-issued mobile phone.

Documents show the AFP considered the matter as being in the most serious category for misconduct.

The Department of Foreign Affairs and Trade did not comment. The AFP said it could not comment because the case was being heard at Fair Work Australia.

The union that represents officers, the Australian Federal Police Association, has lodged a submission to the parliamentary joint committee on law enforcement calling for more to be done to stamp out corruption.

AFP Association president Jon Hunt Sharman said the Proceeds of Crime Act should immediately be changed so public servants - from officers, to politicians and members of the judiciary - could be charged if they could not explain an increase in their wealth.

Highly sensitive operations in overseas countries by AFP officers is part of the reason the federal police significantly increased its illegal drugs haul and doubled the number of confiscated assets last year.

''[Corruption] puts at risk the safety and professionalism of our members, who are actually keeping Australia safe and protecting all Australians from criminal attack,'' Mr Hunt Sharman said.

The AFP Association's submission said the existing title of the Proceeds of Crime Act was misleading.

''It actually requires a link to criminality therefore it is not an unexplained wealth provision, which makes the provision inoperable,'' the submission said.