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.
"We are committed to working with the union to find a resolution, but after 18 months we need to take a new approach. We are very keen to settle a collective agreement, so the next sensible step is to apply for urgent facilitated bargaining with the Employment Relations Authority.
"We are in the process of making our application. Out of respect for the process and to ensure the facilitated bargaining has the best chance of being successful, we will not make any further comments to the media until we have an outcome from the Employment Relations Authority process."