BILLINGS, Mont. — More signs of problems have emerged with an Australian company’s bid to take over a Montana coal mine near the Wyoming border, as court documents reveal Ambre Energy has been unable to come up with more than $70 million in cash to close on the deal.

The Decker mine is co-owned by Ambre and Wyoming-based Cloud Peak Energy. Ambre wants full ownership as part of its ambitious plans to ramp up coal exports to Asia through two West Coast ports.

Decker last year was the subject of a management quarrel between its owners that led to a lawsuit in U.S. District Court. The two sides struck a tentative deal in December — shortly before about a third of the mine’s workforce was laid off — but have since asked the court to extend their settlement deadline three times.

The latest request, to push back the deadline from Friday to Aug. 30, was granted earlier last week by U.S. Magistrate Judge Carolyn Ostby. The judge indicated that this will be the final chance for the companies to work out a deal before the lawsuit proceeds to trial in September.

Cloud Peak and Ambre said in court documents that their ability to close the sale depended on “Ambre’s ongoing financing efforts to obtain cash collateral.” That cash is needed to cover