Myanmar police say they have seized a huge haul of liquid fentanyl, the first time one of the dangerous synthetic opioids that have ravaged North America has been found in Asia's Golden Triangle drug-producing region.

In a signal that Asia's drug syndicates have moved into the lucrative opioid market, more than 3,700 liters of methylfentanyl was discovered by anti-narcotics police near Loikan village in Shan State in northeast Myanmar.

The seizure of the fentanyl derivative was part of Asia's biggest-ever interception of illicit drugs, precursors and drug-making equipment, including 193 million methamphetamine tablets known as yaba. At 17.5 metric tons, the yaba almost equaled the amount seized in the previous two years in Myanmar.