Dutch police have dismantled 42 laboratories producing the party drug ecstasy this year, up from 29 in 2012 and almost double the 2011 total, Nos television reported on Friday.

Police have also been alerted to almost twice as many dumps of left-over chemicals this year as in 2012, indicating production is up sharply, the justice ministry figures show.

Most of the pills produced in the Netherlands are destined for foreign consumption. The trade is lucrative because Dutch ecstasy is of high quality and is much more expensive in other countries than in the Netherlands, Nos said.

The labs are mainly located in Brabant, where marijuana growers are making the switch to other drugs.

Police also seized 60,000 kilos of chemicals used to make the drug so far this year. Half of this was found in the Netherlands, the other half was in the process of being shipped to Dutch buyers.