Mitsubishi said it had also agreed to grant Yancoal a call option to purchase its 28.9% interest in the Warkworth operation for $230 million.

This would bring Yancoal’s offer for Mitsubishi’s stake in both Warkworth and HVO to $940 million – $20 million higher than Glencore’s offer.

In Glencore’s bid for Rio Tinto’s majority owned Coal & Allied coal assets in New South Wales’ Hunter Valley, the company said it wanted to purchase Mitsubishi's 32.4% interest in the HVO JV and 28.898% interest in the Warkworth joint venture for US$920m cash conditional on completion of Glencore's acquisition of C&A from Rio Tinto, with $520 million being payable on completion and $100 million payable on the first four anniversaries of completion.

 “The Tag–along Offer fulfills Yancoal’s obligation to make a ‘tag-along offer’ to Mitsubishi under the sale and purchase agreement for Yancoal’s acquisition of 100% of the shares in Coal & Allied Industries Limited from wholly owned subsidiaries of Rio Tinto and the corresponding requirements of the Hunter Valley Operations Joint Venture Agreement,” Yancoal said in a statement.

“Yancoal and Mitsubishi are now subject to a binding agreement for Yancoal to acquire Mitsubishi’s 32.4% interest in the HVO JV. The Mitsubishi transaction is conditional on completion of the CNA transaction, as well as receipt of necessary regulatory approvals.”