UPDATED 8.10pm More than 1000 Auckland bus drivers will go on strike this Friday to protest their work conditions.

The Tramways Union issued NZ Bus with the strike notice at 11AM this morning.

Drivers are planning to picket at the company's Swanson Depot for the 24-hour work stoppage.

Around 135,000 commuters are expected to be affected, with disruptions to Metrolink, North Star, Go West, Waka Pacific, City Link, and Outer Link bus services.

Howick and Eastern bus drivers are understood to also be participating in the strike.

The drivers say their employer, NZ Bus, is increasing their working hours without providing toilet breaks.

However, NZ Bus said it's both surprised and disappointed by the news of Friday's strike.

Northern chief operating officer Shane McMahon said the company seemed to be making good progress in its discussions with the bus unions last week.

He said NZ Bus drivers enjoy the best terms and conditions in the industry and are paid twenty-dollars-forty an hour, with additional overtime rates.

Mr McMahon said drivers get short breaks between bus trips to go to the toilet, and they're working with Auckland Transport to increase the number of toilet facilities.

He says work hours are in line with industry rules set by NZTA, and issues about long work hours should be taken up with central Government.