A gang of 15 Malaysians has been arrested in Thailand for trying to smuggle millions of dollars worth of heroin and methamphetamine by train, police said Thursday.

Investigators said the group was moving drugs from northern Thailand to the Malaysian town of Butterworth.

"This gang chose to transport drugs by train rather than by car because transporting by car is riskier as there are several checkpoints," Lieutenant General Thitiraj Nhongharnpitak, commander of Thailand's Central Investigation Bureau, told reporters.

Railway police made an initial arrest on Wednesday afternoon following a tip-off, taking in two suspects allegedly in possession of 23 kilogrammes (57 pounds) of methamphetamine.

Their detention led to subsequent raids along the trainline between Thailand and Malaysia, with 12 more suspects arrested and a total of 226 kilos of methamphetamine and eight