The leader of Tonga's Human Rights and Democracy Movement, Lopeti Senituli, says he hopes tough new drug laws will deter the rising number of high school students turning to drugs.
The government has lifted the maximum penalty for drug smuggling to 30 years hard labour or half a million US dollars fine - or both.
The new law also means that anyone found guilty of cultivating or distributing illegal drugs will be fined 340 thousand US dollars or given 25 years hard labour - or both.
Mr Senituli says stiffer penalties are appropriate because there has been a major increase in drug use and abuse in the past 18 months.
He says marijuana is readily available to the young.
"'There has been certainly a marked increase in the incidence of drug use and to a great extent the increase in drug use has been amongst high school and young people."
Mr Senituli says he hopes the new law will also deter smugglers.