In what could be a firm testament to Australia's mining regime deceleration, another buyout acquisition has turned pffft.

On Friday, Whitehaven Coal Limited announced that major shareholder electrician-turned-mining magnate Nathan Tinkler and his Tinkler Group is no longer interested in pursuing a takeover bid for the company, worth $5.2 billion or $5.20 cash per share.

Industry observers opined Mr Tinkler could have been unable to gather enough funding for the bid, thus the cancellation, two months after he approached Whitehaven Coal with a takeover proposal. Although in July, the Tinkler Group said it had enough funding support. The company also shared that at least 48.3 per cent of shareholders had agreed to be part of the bid.

Last week, it was reported that the rags-to-riches Mr Tinkler had been divesting his interests in the racing industry, which observers say were part of efforts to raise money. Mr Tinkler has been reported to have missed deadlines earlier this month in settling obligations to coal junior Blackwood for a $28.4 million stake in the latter.

"The due diligence period expired yesterday and Whitehaven has now been advised by the Tinkler Group that a formal binding proposal of $5.20 cash per share will not be forthcoming," NSW-based coal producer Whitehaven said in a statement to the Australian Securities Exchange on Friday.

"Accordingly, the data room has been closed and the due diligence process has now ended," it added.

Mr Tinkler maintains a 21 per cent hold in Whitehaven. He majority shareholder when Whitehaven bought his Aston Resources coal company and Boardwalk Resources for $2.7 billion earlier this year.

Whitehaven which has operations and development projects in the Gunnedah Basin and Hunter Valley, as well as Queensland.

Despite the Tinkler Group's bid walkout, Whitehaven said it remains open to considering and accepting takeover proposals, but "would remain focused on developing the company's portfolio of high quality coal assets to deliver value for all shareholders."

Whitehaven shares closed 1.7 per cent lower yesterday at $3.48.