Seven men have been arrested in Portstewart in connection with the seizure of a substantial quantity of illegal drugs on Friday.
The suspected ecstasy haul was estimated to have a street value of half a million pounds.
The arrests were made as part of a major PSNI operation into organised crime in the North West.
Police said seven people are continuing to assist them with their enquiries.
Detective Chief Superintendent Roy McComb Head of the Police Service of Northern Ireland Organised Crime Branch said the North West was a "safer place" as a result of the seizure.
"This was a substantial seizure of harmful drugs which will make a real difference in protecting the communities in what is a busy student and night-time economy area," he said.