Emails from a senior bureaucrat to South32, obtained under freedom of information laws by anti-coal group Lock the Gate, recommended the miner amend its application letter to argue clearly that Dendrobium coal was necessary for the BlueScope steelworks.

When the Independent Planning Commission (IPC) rejected the expansion last year, it questioned the miner's claim that BlueScope depended on its coal.

DPIE director of Resource Assessments Jessie Evans advised South32 to argue this point: "The report doesn't clearly state that coal produced from the project is suitable for use by BlueScope, rather, it states "the new mine plan for Area 5 will produce high quality metallurgical coal suitable for use in steelmaking," he wrote.

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"Given the heavy reliance of the justification for the project on supplying BlueScope, a statement saying the coal meets BlueScope specs (or can meet specs with blending) would be useful," he wrote.

A week later, in another email, he recommended: "One area where the letter would benefit is some additional information in relation to the IPCs commentary around Wongawilli Seam coal being the main supply source for BlueScope".

Lock the Gate NSW co-ordinator Nic Clyde said this was "coaching".

"This apparent coaching of South32 by the department exposes the uncomfortable closeness of the government and the proponents of extremely controversial coal mines," he said.

"The correspondence shows the Planning Department is clearly unable to objectively assess the Dendrobium expansion at arm's length."

Deidre Stuart of the Illawarra Protect Our Water Catchment group said it was "a disgrace".

"At the very least, in light of these revelations, an independent and transparent body must now oversee the assessment of South32's revised Dendrobium proposal," she said.

Through a spokeswoman, DPE defended its "rigorous" assessment process.

"It's common practice to seek further information from applicants," she said.

"In this instance, we required the applicant to demonstrate how the proposal addressed the Independent Planning Commission's concerns, particularly its economic importance.

"The declaration of the project as State Significant Infrastructure does not change our rigorous assessment process. We will undertake a comprehensive whole-of-government merit assessment, in accordance with the requirements under the Environmental Planning and Assessment Act.

"The new proposal, which incorporates changes intended to address the issues raised by the Independent Planning Commission, is on exhibition until 14 June and we encourage the community to have its say."

A South32 spokesman said it had followed standard "protocols".

"South32 has followed standard protocols for the submission of the Dendrobium mine extension project application, including publication of a Scoping Report and an Environmental Impact Statement, which responds to the Secretary's Environmental Assessment Requirements (SEARs)," he said.

"At each step we are required to provide relevant details on our proposals.

"Illawarra Metallurgical Coal currently supplies BlueScope with approximately 60 per cent of its hard coking coal requirements and the existing Dendrobium mine operations are integrated with BlueScope's steelmaking operations at Port Kembla."

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