Authorities believe they've just made the largest ever drug seizure at New Zealand's border

Almost 2000 litres of GBL, known as Fantasy or liquid ecstasy, has been confiscated following a six-month police and customs operation.

Four men aged between 38 and 75 have been arrested in Wellington.

Detective Inspector Darrin Thomson says it's great news for the Wellington region because the drugs have a 14-million dollar street value, and would have supplied more than a million doses.