Two New Zealanders have been arrested in Japan for allegedly trafficking drugs,

Two New Zealanders have been arrested in Japan for allegedly trafficking drugs, prompting police to issue a warning about what they say is a trend of people increasingly becoming drug "mules''.

The 26-year-old man and 25-year-old woman had travelled to Tokyo on the May 17 on a Thai airways flight from Bangkok, Thailand and were allegedly smuggling methamphetamine into Tokyo’s Narita International Airport this month.

The methamphetamine, believed to total between 1-2 kilograms, was found concealed in their suitcase.

The arrests come after another high-profile case. New Zealander Sharon Armstrong,was arrested in Buenos Aires on April 13 with 5kgs of cocaine hidden in her luggage while on her way to London.

Assistant Police Commissioner Malcolm Burgess said people should report any approaches they may get from anyone asking them to carry drugs.

He said people thought they could earn easy money by helping organised crime groups to bring illegal drugs into New Zealand or across borders of other countries.

"The risks these people take are huge.

"We and our partner agencies such as Customs and Immigration are cracking down on organised crime.

"We are finding more and more people are getting caught up in it all for a bit of extra cash or some other benefit.''

Burgess said the "apprehensions'' also came only four months after a New Zealand passport holder died in Thailand after attempting to smuggle methamphetamine internally out of Bangkok International Airport.

The 40-year-old man died in a Bangkok hospital in January after having swallowed packages of methamphetamine, which  
are believed to have burst and caused his death.

Burgess said there were few instances where people were an unwitting "mule", with most knowingly entering into an arrangement to carry drugs.

"The temptation for some people to take the risk is often out-weighed by the cash being offered or some other inducement.

"But the consequences, should they get caught, are life-ruining and inevitably end up with a long jail sentence or potentially harsher penalties if arrested in some overseas  countries.''