Up to 5,000 tyres found in Menai Bridge illegal dump
Between 3,000 and 5,000 tyres have been discovered being stored illegally on Anglesey.
The Environment Agency raided the dump in Menai Bridge and also executed a search warrant at an address in Llangefni.
Officials said the tyres were being stored and sorted at Menai Bridge before being exported to Ghana.
The agency said an enforcement notice would order the tyres removal.
It said North Wales Police were also involved in the raids and it was liaising with the council planning enforcement team.
The agency's Environmental Crime Team leader Jason Westerberg-Liptrot said illegal sites were a hazard.
"Operators who run sites illegally put the environment and human health at risk and undermine legitimate businesses," he said.
"The cost of disposal of a car tyre is in the region of £1.44 per tyre and if anyone offers to take waste tyres away for less they should be treated with suspicion," he continued.
The agency said landlords and agents should always check with its officials before letting out property to companies who deal in waste.