The report shows the department could only provide evidence that it had checked about 60% of management plans.

Greens Senator Larissa Waters said this had allowed mining conditions to flout environmental conditions placed on their projects.

“This means proponents often get their approval with requirements to provide details in later plans as to how they will manage environmental damage, but then those plans aren't properly scrutinised which could be leading to significant environmental damage,” she said.

“The report finds most compliance monitoring is done by phone or email, so big mining companies are being trusted to provide accurate information, without on-site inspections.

“The big mining companies are getting away with flouting environmental conditions, without the departmental capacity or political will to stop them.”

Waters said the government’s budget would cut hundreds of staff from the environment department, including 129 from the division responsible for enforcement.

“This is an incredibly alarming prospect for our nationally significant environmental treasures, such as the Great Barrier Reef, the Kimberley and Cape York, which are all under threat from mining projects,” she said.

“Many projects, including the Abbot Point coal port expansion in the Great Barrier Reef, have been approved with conditions requiring the proponent to provide a management plan on how they will manage environmental risks.”