Senior officials at the Scottish Ambulance Service's (SAS) Headquarters in Edinburgh have been accused by staff of bullying and intimidating them.
The claims were revealed in a letter written to a senior NHS executive.
It has been alleged an official ordered paramedics to move rapid-response vehicles that were parked outside the building so he could drive in with his luxury car.
However, staff refused to move the emergency vehicles and were allegedly taken into an office and reprimanded.
Another manager has been accused of harassing workers after they signed an open letter complaining about the lack of parking spaces for frontline staff.
Some staff claim they had received abusive and threatening calls on their mobiles about the parking issue.
The SAS refuted all allegations.
Labour's health spokeswoman, Jackie Baillie said: "I'm very concerned for any service, particularly the ambulance service, to experience what appears to be an extraordinary level of bullying."
A spokesman for the Scottish Ambulance Service said: "All staff in the SAS should be treated with dignity and respect."