"This is disappointing for us and disappointing for commuters who may be coming back from holiday today and not realise that there have been some bus services affected for tomorrow.
"We are working through which bus services have been affected and figuring out how we are going to minimise those impacts right now so we should know this afternoon what the impacts will be."
Ireland said the unexpected strike means that AT is quickly working with bus operators to come up with a plan. It hoped to announce what services will be running later this afternoon.
Bus companies were frantically calling bus drivers not scheduled to work tomorrow to see if they could cover the shifts.
Usually the unions would have to give at least 24 hours notification during business hours, he said.
"It's made it more difficult by the fact that it's a public holiday."
The strike will also affect services in Hamilton, with Go Bus drivers embarking in a shorter protest between 5am and 9am tomorrow.
Go Bus chief operating officer Nigel Piper said Hamilton passengers were being needlessly disrupted as the issues related to other regions outside the Waikato.
'We are not surprised by the short-notice strike, but we are disappointed that Hamilton bus services have become targets for national action. We are currently in a facilitated bargaining process with First Union, which we have put a significant amount of effort into, it's difficult to see the same commitment from the union."
Waikato Regional Council public transport operations manager Andrew Wilson said staff were working closely with Go Bus to see if they could resource any other services to minimise the inconvenience to passengers.
The Orbiter and regional services – 20 Cambridge, 21 Northern Connector, 22 Morrinsville/Paeroa, 23 Raglan and 24 Te Awamutu – will operate as normal.
The CBD Shuttle will operate around every 15 minutes and the two 4N Flagstaff North bus services will combine into one service for the duration of the driver strike.
There will be a limited service on the following routes: 1 Pukete, 2 Silverdale, 3 Dinsdale, 6 Mahoe, 9 Nawton and 16 Rototuna.
All other Hamilton bus services would be cancelled during the industrial action.
Auckland bus drivers to walk off job for 24 hours on Tuesday in strike over industry standards