The Bank of Tokyo-Mitsubishi is refusing to agree to Solid Energy's proposed financial restructure, instead launching legal action against it.
Solid Energy believes that if an agreement can't be reached, the state owned coal-miner won't be able to continue to trade and liquidation or voluntary administration will be the likely outcome.
Earlier this month, the Government announced the debt restructure had the support of the State-owned coal-miner's lenders, which it said would give Solid Energy the time it needed to get the business back in reasonable shape.
But it has now emerged that the Bank of Tokyo-Mitsubishi has issued a legal challenge to the restructure, and it hasn't signed up to the agreement in Solid Energy's debt exchange compromise proposal.
The bank issued general proceedings against Solid Energy in the High Court in Auckland on 9 October.
The Bank of Tokyo is Solid Energy's second biggest lender, having entered into an agreement for the debt facility in 2010, and is owed more than $80 million.
The Government's proposal includes restructuring the bulk of the company's bank facilities and issuing $100 million in non-voting redeemable preference shares.
Three quarters of those shares would go to the lenders, essentially swapping debt for equity. The Bank of Tokyo would hold more than 16 million of those shares - if it agreed to the proposal.
Lenders will vote on the restructure at a meeting in Christchurch next week.
ANZ, Bank of New Zealand, Westpac, the New Zealand Branch of the Commonwealth Bank of Australia and TSB have all agreed to the restructure.