Frederic Tiberghien, 55, currently works for a company in the northern Yen Bai Province, according to police of Long Bien District.
Authorities last Saturday discovered around 100 cannabis plants on the islet, alongside a stash of dry weed. A total 115 cannabis plants weighing around 34 kilograms were seized, along with around 40 grams of dry grass.
An investigation is ongoing.
Cannabis is on the list of narcotics forbidden in Vietnam. Those growing cannabis in small scale could be fined VND2-5 million ($86.16-215.40). Farmers found cultivating 500 to 3,000 plants could face jail terms of six months to three years, while those working on bigger scale could spend up to seven years in jail.
Worldwide, increasing numbers of countries and localities are legalizing medical or recreational use of marijuana, including almost 40 states in the United States.