UP TO two dozen illegal handguns - including some bought by Sydney crime gangs - passed through Port Botany after customs officers falsified paperwork to wrongly claim they had X-rayed the container in which the weapons were hidden.
A six-month Fairfax Media investigation - conducted in association with the ABC program 7.30 - also reveals that Customs is investigating about 100 criminal allegations involving its staff, the highest number in the agency's history, and has received more than 1300 allegations of misconduct since 2008.
It has also emerged that the acting chief executive of Customs, Michael Pezzullo, was frozen out of parts of the federal police investigation of corruption at Sydney Airport because his brother, a customs officer, works and associates with several members of the allegedly corrupt Customs airport cell.
In other revelations, which come after Thursday's expose´ of an allegedly corrupt cell of customs officers at Sydney Airport:
Dozens of pages of sensitive Customs documents were leaked to a crime syndicate controlled by a drug and illegal tobacco smuggler, Mohamad Jomaa, who ran a syndicate that boasts of having several contacts inside Customs;
A joint police taskforce has identified up to 12 suspected corrupt customs officials working to secure NSW's maritime borders, adding to the cell of 15 allegedly corrupt officers at Sydney Airport, including some still working there;
Employees of Menzies Aviation with federal government security clearances are being investigated over their links to Customs' alleged drug trafficking. Menzies provides baggage handling services at the airport.
The smuggled handguns were identified by a police operation codenamed Otford that found the guns were smuggled in engine parts that a small number of customs officers had claimed they had scanned. Further investigations have found the officers falsified paperwork to give the engine parts the all-clear.
While they were caught lying about their failure to scan the container, there is no evidence they knew it contained guns.
It is unclear if any of the smuggled guns, which include four semi-automatic pistols recovered by police, have been used in any of Sydney's gangland killings.
Customs has dealt with the case as a matter of misconduct and incompetence and said the officers had been subject to ''code of conduct provisions'' and in October ''received remedial training and workplace counselling''.
But senior NSW Police are believed to have been furious at Customs' role in the affair, especially as it follows a string of so-called "misdetections" by customs staff of drug shipments.
Regarding the continuing airport probe, there is no suggestion Mr Pezzullo's brother is involved in corruption. (Fairfax made several attempts to contact Mr Pezzullo's brother but was not successful.)
One of the aspects of the investigation is whether customs staff not involved in corruption nevertheless knew that some of their colleagues might have had inappropriate associations or might have been engaged in questionable behaviour in or outside work hours.
At least four officers still working at the airport attended the court case of an allegedly drug-using officer without informing their bosses.
Asked about his brother's relationship with suspected corrupt customs officials, Mr Pezzullo said: "I was advised by the previous CEO that I was to be excluded from all briefings and information related to allegations concerning possible corrupt activities at Sydney Airport on the basis that I had a family member who worked at the airport."
Of the suspected corrupt customs officers on the waterfront identified by the joint agency Polaris taskforce, several are suspected to be involved in facilitating illegal tobacco or drug importations. A confidential Polaris report from this year states that Customs Examination Facility at Port Botany has been "infiltrated" by criminals.
"Polaris investigations demonstrate links between CEF staff [including customs officers] and criminal syndicates which are involved in the importation of illicit drugs and tobacco into Australia," it says.
One of the customs officials suspected to be aiding maritime drug and tobacco imports was allowed access to highly sensitive information, despite having two brothers known to NSW Police as drug traffickers.
This officer was also one of at least two customs staff with strong ties to a crime syndicate led by Mohamad Jomaa, as well as two alleged tobacco smugglers who are before the court and who are facing charges of bribing a third customs official.
Asked about the suspected corrupt customs officer with links to Jomaa, Mr Pezzullo told Fairfax he "chose to resign while Customs … was making an assessment of his suitability to continue to hold a security clearance".
Dirk Scott, the general manager of Menzies Aviation, said on Thursday he had heard nothing from federal police or the federal government about any of his staff having suspected links to allegedly corrupt customs officers or crime figures.