Seven men have been arrested after drugs worth an estimated £500,000 were seized by police in the Portstewart area.
The suspected ecstasy haul was discovered as part of a pro-active police operation into organised crime in the north west.
David McClarty, Ulster Unionist East Londonderry MLA, said the seizure amounted to half a million pounds worth of misery taken off the streets.
"I congratulate the PSNI on both the seizure and the arrests in Portstewart, and would urge members of the community to work with police to make this drugs scourge a thing of the past," he said.
"The good people of Portstewart and surrounding areas will feel confident that sterling work is being done to protect the young people within our communities from those seeking to profit from the misery of drug abuse."
Detective Chief Superintendent Roy McComb, head of the PSNI's Organised Crime Branch, said officers were committed to tackling organised crime gangs involved in the distribution and supply of dangerous drugs.
"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.