Contract talks have broken off between the Public Service Alliance of Canada and the Treasury Board over a new contract for Canadian Border Services Agency workers.
The breakdown comes after three days of mediation.
The union says working conditions and compensation are the key issues in the dispute.
PSAC represents 8,000 border workers who have been without a contract since 2014.
The union says it now plans to take the next step in the process - filing for a Public Interest Commission.