Wellington, Jun 19 (IANS): Four Nigerian nationals and a New Zealander have received jail terms for their involvement in an international drug smuggling ring, New Zealand Police said on Friday.

The Nigerians were jailed for terms of 15 to 18 years after being found guilty of importing and possessing methamphetamine for supply, and the New Zealander was jailed for nine years for possession of methamphetamine for supply.

The sentences handed down at the Auckland High Court on Thursday marked a successful end to a combined police and customs operation that began in November 2013, Xinhua reported, citing a police statement.

Operation Gatsby was launched after customs officers discovered methamphetamine with a street value of $1.5 million NZ ($1.04 million) in the luggage of an Auckland man who had just returned from Port Moresby in Papua New Guinea.

Detective Senior Sergeant Lloyd Schmid said officers determined that the man had been duped and used as a drug mule by an international syndicate and launched an operation to track the destination of the methamphetamine.

During the five-week investigation, they identified two further imports containing over 1.2 kg of methamphetamine, said Schmid.

"Both had been sent to New Zealand through the international mail system from the Philippines and Cameroon," he said.

"Operation Gatsby demonstrates that the New Zealand drug market is being targeted by organised crime syndicates from every corner of the globe."

In August last year, a 39-year-old woman was jailed for four years for possession of methamphetamine for supply, and in January this year, a 40-year-old man pleaded guilty to a similar charge and was jailed for five years and eight months.