A large number of Metrobus commuters were left stranded on Friday morning due to a driver's strike at the Village Main depot in Johannesburg, the company said.

"Only the those passengers making use of the buses operating in the south are affected... the other two depots are unaffected," said spokesperson Esther Dreyer.

She said the strike was illegal because both Metrobus unions, the South African Municipal Workers Union and the Independent Municipal and Allied Trade Union, had not asked for permission.

Although she could not say what the strike was about, Dreyer said they were talking to both unions and hoped everything would be resolved by the end of the day.

"We can't say how long it will take, it's unpredictable... but we're hoping for good news towards the afternoon."

She said a management was making a "concerted effort" to resolve the dispute.

"Metrobus extends its apologies to all passengers who were inconvenienced due to this industrial action."