A bus driver on the Port Chalmers to Dunedin City route has been stood down while the Otago Regional Council and Ritchies investigate allegations of lewd behaviour towards female passengers.

Otago Regional Council stakeholder engagement director Sian Sutton said yesterday staff were in "close contact" with bus service operator Ritchies while the matter was investigated.

"We've taken the complaints very seriously."

Another email, sent by council transport officer Letitia McRodden and posted on a Port Chalmers community online page, provided more information.

The email was in reply to an alleged victim of the driver after she complained to the ORC about the driver's conduct.

According to the email, Ritchies' management and the ORC, which is responsible for Dunedin public bus services, were undertaking a joint investigation into the driver.

"Ritchies management believe they have identified the driver concerned and he has been stood down from the service for the duration of the investigation," it said.

Ritchies Dunedin and Queenstown area manager Peter Varrie confirmed an investigation was under way, but referred all other questions to the council.

Multiple other complaints about inappropriate behaviour by the driver have also been posted on social media.

Asked if police had received any complaints about the driver on that route, a spokeswoman said they were "not able to respond to requests ... " without providing the date, time or name of alleged victim.