Tinkler, who now resides in Singapore, would seek an offtake and equity partner such as Noble to secure the proposed privatisation, which comes less than two months after the $5.1 billion merger between his Boardwalk and Aston Resources and Whitehaven was completed.

Other media reports indicate Tinkler is reportedly seeking equity support from Farallon Capital, the Kuok Group and Japan's Electric Power Development Co (J-Power), which owns 10% of Whitehaven's Maules Creek mine in New South Wales.

Analysts were quoted in the Australian Financial Review as saying that he would need to make an offer with a healthy premium above its current price of $4.19. A bid above $6 per share would be a minimum, they reportedly said.

If he decided to go down the debt route he would need to borrow at least $2.5 billion to pay for the 78.6% of the company he does not own and is reportedly in discussions with UBS and JPMorgan, according to Reuters.

Tinkler’s bid is an “indicative, non-binding proposal", Whitehaven said in a statement.

“The proposal is highly conditional and incomplete and is not considered capable of being progressed at this time,” it said.

On the possibility that a less conditional and more complete proposal might ultimately develop from this preliminary approach, the directors of Whitehaven had taken steps to ensure the independence of Whitehaven’s response and had established a committee of directors not associated with the bidder to consider any future developments, it said.