Zeeland police have found enough chemicals to produce one billion ecstasy pills in a lorry and trailer left on a car park in the town of Rilland.

The chemicals, including 15,000 kilos of caustic soda, had a combined value of several hundred thousand euros, police said in a statement.

The lorry was opened after a tip-off from a local warden who noticed it had been left in the lorry park for several days.

Police are now trying to trace the owner of the lorry in an effort to find out who owned the chemicals.