The investigation began early last year around the border with Belgium and was extended further north into the Netherlands. It also involved Spain. On Monday, police raided homes and business premises in the Netherlands and Belgium.

Eight people were arrested in the Netherlands, and six in Belgium. No one was held in Spain despite one address being raided.

In the Netherlands, 200,000 ecstasy pills, 2.5 kilos of cocaine, a number of kilos of amphetamine and 250 litres of GHB were confiscated. Four cannabis plantations, eight guns, and large amounts of cash were also discovered.

Around 200 Dutch and 125 Belgian police were involved in the operation.