The police have sent three truckloads of illegal waste back to the Republic of Ireland after it was seized by officers.
Six lorries were intercepted in a joint operation
Last week, police seized six lorries and trailers as part of an operation to combat the activity.
Detective Chief Inspector Esmond Adair said illegal dumping was a growing problem that was costing millions to Northern Ireland taxpayers.
"Recently we have had some indications that organised criminals are becoming involved in this activity," he said.
"Undoubtedly some hauliers are involved as well."
Speaking on Tuesday, he said the PSNI would be carrying out further operations in the future.
It is believed that hauliers involved in this type of scam are based in Northern Ireland.
Last Wednesday's seizure followed a two-day operation between Newry and Lurgan, conducted by the PSNI, the Department of Environment and Garda Siochana.
It is thought the waste may have been smuggled across the border to be dumped illegally in the north.