BUS services in the Adelaide Hills on Friday morning are being threatened by strike action by drivers.

Transport Workers Union members have voted to take industrial action as the result of a stalemate in Enterprise Agreement negotiations with bus operator Transitplus, which services the majority of the Hills through Lobethal, Strathalbyn, Mt Barker, Aldgate and Stirling to the city via Glen Osmond Rd.

Transitplus advises passengers that the potential disruption could affect services from 5.30am to 9.30am at least.

Both the bus company and the union say they are focusing their efforts on avoiding what both term "unnecessary disruption". However neither has indicated it is prepared to budge on the agreement.

Transitplus general manager Mark Dunlop said the company had clearly stated its final wages position and unsuccessfully tried to avoid strike action by going to Fair Work Australia to negotiate a resolution.

"Transitplus has put forward an excellent offer of 4.48 per cent plus changes to agreement penalty terms which puts the wage increase being offered in excess of 4.5 per cent," he said.

"This puts our drivers at the top of bus drivers rates paid within Adelaide, so it is disappointing that strike action has been initiated by the TWU."

Mr Dunlop said that if the stalemate could not be broken, passengers including thousands of school children would be subjected to unnecessary disruption.

Transport Workers Union SA branch secretary Alex Gallacher said the union was happy to resume talks with Transitplus at any time in a bid to avoid strike action but that members were not happy with the company's offer.

"The way the award is constructed is very important to our people, but they (Transitplus) want to offer less in some areas to fund a wage increase," he said.

"There's a little bit of time to fix this - it's only Tuesday. We're ready to meet between now and Friday morning and think we're not that far apart."

If strike action goes ahead on Friday, services are expected to be gradually phased back in from 9.30am.

Services that could be affected include the 820-823, 830, 834, 835, 837-842, 847-850, 852, 860, 861, T863, 863-866, 868, 870-873, 875, 877, 879, 880-888, 890-894, 896-899 buses.

Originally published as Strike action threatens Hills buses