A Dublin tour operator says he is considering pulling out of bringing visitors to Derry because of repeated attacks on his coaches.
Liberty Tours, based in Dublin, says vandals are costing the company thousands by breaking windows in parked coaches.
The Paddywagon company has had trouble in Belfast from sectarian attacks but these in Derry appear to be mindless vandalism.
In the latest attack, a coach run by Liberty Tours had its windows smashed and an attempt was made to set it on fire in the Bogside.
Sean Martin from Liberty Tours said they were not alone and other operators' coaches have also been attacked.
In an unrelated incident in Derry, a tour guide has called for a greater police presence on the city's famous walls after her tour was verbally abused by drunken youths.