Go Bus says it is urgently applying to the Employment Relations Authority to seek facilitated bargaining with First Union over ongoing collective agreement negotiations with drivers.
The company said the application was an attempt to conclude the "protracted negotiations".
The 18-month long negotiations are around pay and conditions for Waikato and Bay of Plenty urban and school bus drivers.
Nigel Piper, chief operating officer of Go Bus, said the company had long been committed to working with the union to find "a sensible agreement that will benefit all parties".
However, Piper said it became evident in Friday's mediation that the parties needed further assistance to reach agreement.