A pregnant Auckland woman and her partner are among the rising number of New Zealanders caught smuggling drugs into other countries for "a bit of extra cash".
They include one man who died in a Thai hospital.
The couple, aged 26 and 25, are in a Japanese prison after 1kg-2kg of methamphetamine was found in their luggage after they left Bangkok in Thailand.
That amount of P would fetch up to $2 million in New Zealand.
The pair were heading home via Tokyo when they were stopped at Narita International Airport on May 17.
It is understood the 25-year-old woman is in the late stages of her pregnancy.
Another New Zealand passport holder died in Thailand after swallowing parcels of methamphetamine to smuggle out of the country in January.
He boarded a plane at Bangkok International Airport, but left it again after feeling ill. The 40-year-old man, of Iranian descent, is believed to have died in hospital from an overdose after the packages burst inside him.
The latest drug mule case in Japan happened weeks after Wellington woman Sharon Armstrong was arrested in Buenos Aires with 5kg of cocaine hidden in her luggage.
Senior police officers are worried at the increasing numbers of New Zealanders caught as drug trafficking "mules" through the border and warning people to report any approaches for them to carry drugs.
Assistant Commissioner Malcolm Burgess said the trend was concerning, as some people thought they could make easy money by helping organised crime groups bring drugs into New Zealand or other countries.
"The risks these people take are huge," he said.
"We and our partner agencies such as Customs and Immigration are cracking down on organised crime.
"Easy cash turns Kiwis into drug dupes.
"We are finding more and more people are getting caught up in it all for a bit of extra cash or some other benefit," Mr Burgess said.
There were a few instances where the traveller might be an unwitting "mule".
But Mr Burgess said most knowingly agreed to carry drugs. "The temptation for some people to take the risk is often outweighed by the cash being offered or some other inducement. "
Some countries, such as Indonesia, have the death penalty for drug smugglers.
Mr Burgess advised anyone approached with a tempting offer to work as a drug mule to contact police, Customs or Crimestoppers.
A Ministry of Foreign Affairs and Trade spokeswoman said the New Zealand Embassy in Tokyo had been in contact with the arrested Auckland couple. New Zealand was unable to intervene in the judicial processes of another country, she said. Sharon Armstrong (54) was arrested in April when 5kg of cocaine was found hidden in her luggage at Buenos Aires Airport.
The former Maori Language Commission deputy chief executive is imprisoned in Unidad 31, a medium-security prison 30km southwest of the Argentinian capital.
She admitted she knew about a parcel hidden in her suitcase but says she believed she was taking a top-secret business contract to London to give to a man she had been dating online for six months.
