A New Zealander has been arrested in Thailand for allegedly attempting to smuggle heroin into Phuket on a yacht.

According to the Taiwan newspaper the China Post, Kerry Graeme Mitchell, 49, was arrested with his Thai wife and two Hong Kong nationals near the port of Phuket on Friday.

The China Post says Mitchell is being held in a Bangkok prison and faces a death sentence if convicted.

Thai police believe the four bought the heroin in Myanmar and were planning to ship it via a private yacht to Hong Kong and Australia for sale.

New Zealand's Ministry of Foreign Affairs says it is aware of Mitchell's arrest, but says he has not requested any assistance from New Zealand.

Thailand has some of the toughest drug laws in Asia and scores of foreigners face the death penalty for drugs convictions.

Kerry Graeme Mitchell, 48, was arrested along with two Hong Kong citizens and a Thai for trafficking around 40kg of heroin.

The heroin had an estimated street value of more than $4 million.

The police say it was orginally smuggled into Thailand from the notorious Golden Triangle drug-producing region of western Myanmar and northern Laos.

They allege it was handed over to Mitchell in Phuket and say he ultimately intended to sell it in Australia.

A New Zealander being held in Thailand for allegedly attempting to smuggle 40kg of heroin left Blenheim about 15 years ago.

Kerry Graeme Mitchell, 49, could be sentenced to death if convicted.

With a street value of $1000 a gram, the heroin haul would be worth $40 million in New Zealand.

Mitchell, a former Marlborough Boys' College student who is believed to have left Marlborough in the late 1980s or early '90s, and his Thai wife Sangvan Newton were arrested on Friday.

Earlier in the day, two Hong Kong nationals - Leung Chun Yu, 20, and Barry Chung Oi Fung, 42 - were detained with the heroin and later implicated Mitchell, Lieutenant General Wacharaphon Prasanrachakit of the Thai police said.

The four are being held in a Bangkok jail. Thailand has some of the most draconian drug laws in Asia and scores of foreigners are on death row for drug-related convictions.

Mitchell also allegedly held a fake British passport under the name Ian James Newton, Mr Wacharaphon said.

Authorities believe the four were planning to ship the heroin - bought in Myanmar - via a private yacht to Hong Kong and Australia for sale.

49-year-old Kerry Graeme Mitchell has been picked up for allegedly attempting to smuggle 40 kilograms of heroin out of Phuket.

Thai police say two Hong Kong nationals implicated Mr Mitchell after they were detained with two suitcases of heroin.

They believe the group was planning to ship the heroin to Australia.