The argument is over the Decker Mine that Cloud Peak subsidiary Western Minerals runs 50-50 with Ambre (pronounced Amber) entity KCP.

Ambre bought its 50% stake in the Decker mine when it bought KCP last November.

It also has been working to develop port infrastructure on the US west coast.

In documents filed with the US District Court in Montana Cloud Peak claims Ambre plans to force a significant change in the long-standing arrangements by redeveloping the mine for planned future Asian exports.

“However, among other significant concerns, the Ambre entities’ export redevelopment proposition is not that the Decker Coal Company should sell coal from the Decker Mine to Asian utilities with an equal return to both 50 per cent owners,” its filing says.

“Rather, they propose that the Decker Coal Company should sell coal from the Decker Mine to Ambre Entities so the Ambre Entities can retain undisclosed revenue and profits from such coal, while Western Minerals bears 50 per cent of the expense and risk of redevelopment of the mine.

“When Western Minerals expressed concern about an April 30 2012 Ambre Limited press release regarding an unauthorized Ambre Limited sales contract with Korean utilities and explicitly mentioning the Decker Mine, [Ambre Energy North America chief executive officer and president] Everett King brushed off the inquiry, saying such activities ‘did not require a discussion’ with Western Minerals”

In a statement Ambre says Western Minerals self-dealing transactions accusation “presupposes that Cloud Peak is entitled, through its interest in Decker, to access Ambre’s port infrastructure, which is simply not the case.

“Ambre’s infrastructure division is engaged in the permitting and pre-construction of phases of two export infrastructure projects in the Pacific Northwest”

Reading between the lines, it appears Ambre is accusing Cloud Peak of using the dispute to gain access to those ports.

Western Minerals also alleges KCP has mismanaged the mine by operating outside approved budgets and mine plans.

Ambre has hit back saying Cloud Peak and the previous co-owner of Decker had been unable to agree to a mine plan or budget for 2012.

This, it said, forced KCP to manage the mine without an approved budget or mine plan, something it had done well in the circumstances.

“Since filing their lawsuit against KCP, Cloud Peak has even recognized Decker management’s good stewardship over the mine when, on July 12, representatives of Cloud Peak toured the mine and expressed to management that ‘good work’ was being done on reclamation activities,” Ambre said.