More than 250 tyres have been dumped at a nature reserve in the Belfast Hills.
Ulster Wildlife has appealed for information about the incident at Slievenacloy Nature Reserve - an area of special scientific interest.
Lisburn & Castlereagh City Council removed the tyres and is now investigating the incident.
It is thought the tyres - which were dumped over a gate at the facility - could be from a garage or waste contractor.
Staff said fly-tipping is not uncommon at the wildlife haven, with tyres, furniture and cars dumped over the years.
Deborah McLaughlin, nature reserves officer with Ulster Wildlife, said: "Fly-tipping is a growing problem at Slievenacloy, and across the wider Belfast Hills, but this is the worst we've experienced yet.
"Slievenacloy is a beautiful and protected wildlife haven, where orchids, butterflies and birds can thrive and visitors can enjoy nature.
"We would urge businesses and individuals to correctly dispose of their unwanted waste either through certified waste contractors or at their local recycling centres to help us protect and care for special places like this on their doorstep."
Tommy Jeffers, chair of the environmental service committee at Lisburn & Castlereagh City Council, said illegal dumping was an "abhorrent crime".