Bank of Ireland is taking legal action against Brinks Allied following the security firm's decision to withdraw cash services from the bank's Dublin branches and ATMs.
In a statement this afternoon, the bank said supplies at 89 of its ATMs have been disrupted because of a dispute over the terms of its contract with Brinks Allied for the transport of money.
The dispute is understood to centre on who should incur the liability for losses of cash from robberies.
The Bank said that Brinks Allied - in a letter last Friday - had sought its acceptance to "substantial changes in the existing contracts" and had indicated that "failure by the Bank to immediately agree to the changes would lead to withdrawal of all services".
The Bank said it considered "this ultimatum from a key service provider to be unacceptable and clearly in breach of the current contracts".
It said: "At all stages the Bank stated its willingness to meet and discuss operational issues and the current withdrawal of service is disappointing.
"As a result of this action, the Bank has no option but to seek an injunction restraining Brinks Allied from reneging on its contractual obligations during any negotiation," it added.