Environment officials questioned use of land government already owned as offset for western Sydney airport

Exclusive: Green group decries infrastructure department's dodgy offset' plan to use government site that already had protections

Federal environmental department officials questioned the credibility of a government plan to use heritage-listed land it already owned as the main environmental offset for the western Sydney airport.

Documents obtained by Guardian Australia under freedom of information laws show officials asked the federal infrastructure department to justify the use of Defence Establishment Orchard Hills to offset the destruction of more than 100ha of critically endangered Cumberland Plain woodland and other habitat.