Mende – who resides in the US – is president of 5% Whitehaven shareholder AMCI Group, which is also an investor in Bandanna Energy, White Energy and mines owned by Aquila Resources. He is believed to be cashed up and looking to take the opportunity to acquire coal assets at historically low prices following the European debt crisis.

According to the Australian, Mende refused to rule out joining Tinkler’s planned takeover of the New South Wales producer.

Whitehaven Coal said in a statement that Mende’s resignation was consistent with his decision to scale back his international board commitments.

Mende has been closely involved in the development of the company since prior to the company’s initial public offering in 2007.

“Hans has played a significant and valuable role in the development of Whitehaven and its growth from a single mine operation to the largest coal miner in the Gunnedah Basin,” Whitehaven Coal managing director Tony Haggarty said.

Whitehaven Coal chairman Mark Vaile said Mende’s contribution to the Whitehaven board had been “significant”

“Hans has a wealth of experience that has proven very valuable to the Whitehaven board since it was formed,” Vaile said.

Last month Tinkler lobbed his privatisation bid for the miner less than two months after it merged with Boardwalk Resources and Aston Resources in a $5.1 billion deal.

Tinkler, who now resides in Singapore and is a 21.4% shareholder in Whitehaven, wasted no time in making his offer, which the company said was still at a preliminary stage.

Tinkler is believed to be preparing his finances for the $5 billion he needs to acquire the rest of Whitehaven.

Whitehaven’s directors, excluding Mende, have formed a committee to consider any formal offer, which would require entry into a data room.