Multiple arrests in Wellington after what's believed to be the biggest border drug bust in New Zealand

Almost two thousand litres of GBL, known as Fantasy or liquid ecstasy, has been confiscated following a six-month long Police and Customs operation.

Four men aged between 38 and 75 have been taken into custody, and will appear in court next month on a range of significant drug charges.

Detective Inspector Darrin Thomson says the drugs had a 14-million dollar street value, and would have supplied more than a million doses.

As part of a joint operation, Customs also intercepted more than 10 kilograms of methamphetamine.