Customs has refused to disclose whether Australian border protection vessels were turning asylum seeker boats back when they breached Indonesian territorial waters on six occasions.
The incursions took place between December 2013 and January 2014 under Operation Sovereign Borders and the discovery of the "inadvertent" breaches prompted the Abbott government to issue a swift apology to Indonesia.
Customs and Defence conducted a joint internal review into the incidents but only the executive summary with five recommendations was publicly released in February.
But a copy of the full report, under Freedom of Information laws, shows that damage to international relations and national security and defence are cited as reasons for the 18 blacked out pages and other redacted sections.
The document shows the joint review actually made seven recommendations but two have not been made public.
Sections identifying which boats were involved and the circumstances are also blanked out.
The discussion about the Abbott government's policy parameters on boat turn backs - only when safe and outside 12 nautical miles from Indonesia's archipelagic baseline - was also heavily redacted.
Last month, a Senate inquiry into the breaches found those two aims may not be achievable.
The document, obtained by AAP, shows the review team made up of three Defence personnel, and two Customs officers sought advice from the Attorney General's Department and Department of Foreign Affairs but the names of other bodies were blanked out.
It said the review took into account the potential for further inquiry into the events as a justification for making no findings against individuals.
The report said territorial seas declared by foreign nations are generally not depicted on Australian hydrographic charts.
The review blamed the breaches on incorrect calculations of boundaries of Indonesian waters rather than deliberate actions or navigational error.
The breaches have added to tension in Australian Indonesian relations following allegations Australian spies tapped the mobile phones of President Susilo Bambang Yudhoyono and his wife in 2009.
Customs and Defence are still assessing whether lapses in judgment contributed to the breaches.
Training regimes are under review and revised force preparation training will be introduced by May.
Officers will also be given special training on the United Nations convention of the law of the sea from the end of June.