Customs said three foreign nationals, all aged 24, had tried to smuggle in the drugs from Singapore.

The MDMA, or ecstasy crystals, was revealed when X-rays uncovered false bottoms in their suitcases.

The 12kg of drugs had an estimated street value of up to $5 million.

Customs investigations manager Maurice O’Brien said criminal syndicates may think the busy holiday season was an ideal time for drug couriers to hide amongst the crowds, but Customs carried out profiling using data and technology to identify high-risk passengers.

That was supported by frontline capabilities as part of a layered approach.

“In this case, cooperation with our partner agency Ministry for Primary Industries resulted in the seizure and arrests, re-enforcing the effectiveness of our collaborative approach,” O’Brien said.

“Meth is still the main choice for drug couriers and like meth, New Zealand’s price for MDMA is amongst the highest in the world making us an attractive market for criminals. Whatever the drug, Customs is committed to preventing it from getting onto our streets.”

Three men have been charged importing a class B drug. They are scheduled to reappear in the Manukau District Court on January 27.

If convicted, the men face a maximum penalty of 14 years’ imprisonment.