Vandalism at a sewage plant could cause an environmental catastrophe, NI Water has warned.
There have been 24 separated incidents at the water treatment works in Annsborough, Co Down during the last year.
NI Water has spent £100,000 repairing and replacing damaged computers and other equipment. More stringent security measures have also been introduced at the plant which treats raw sewage for 2,100 properties in Castlewellan and Annsborough.
Alec McQuillan, head of Wastewater at NI Water, said there was a risk that rivers could become polluted if equipment was tampered with.
He said: "These incidents have been going on for about a year and have resulted in considerable expense and disruption.
"That expense creates a drain on limited resources, and means that other priority improvements to our services cannot be delivered. However, what worries us more is the potential for a major pollution incident to occur as a result of the damage being caused.
"This area has a well-deserved reputation for the beauty of the waterways and coastline and we, as a company, view the protection of that environment as a major priority. It is for this reason that we are particularly concerned about the potential that these attacks have to cause a significant incident."
Police Service chief inspector Deirdre Bones described the vandalism as senseless. She said: "I would appeal to whoever is responsible for these attacks to stop now before even more serious damage is caused. I am also appealing to the public in the area to be vigilant and if they have any information or see anything suspicious to contact the PSNI in Newcastle police station."
SDLP MLA for south Down, Margaret Ritchie has condemned those responsible for the crimes.
Ms Ritchie said: "Those people who are causing damage at the plant are also putting the wider community at risk of a serious pollution incident and they should stop to consider the ramifications of their mindless vandalism."