Whitehaven said the one month due diligence process began on July 23, rather than the July 13 date the Tinkler group announced its proposed non-binding privatisation offer for the New South Wales coal producer.

“On July 13, 2012, Whitehaven Coal Limited announced that it would grant the Tinkler Group access to due diligence in order to further develop an indicative and non-binding proposal for a Tinkler Group-led bid vehicle to take Whitehaven private for $5.20 cash per share,” Whitehaven said in a statement.

“The due diligence period commenced on July 23, 2012, when the parties executed a confidentiality agreement, and is due to expire on August 23, 2012.

“The due diligence process is progressing.”

Tinkler recently told Bloomberg “the market is valuing assets very differently to how long-term investors value them”

“The market is probably valuing things at half what they’re really worth, in particular when you have a suite of assets that are in development,” he reportedly said.