BANGKOK:Thai authorities on Friday burned more than $225 million of seized drugs – including 21 million amphetamine tablets – as the kingdom ramps up efforts to stem the flow of narcotics in the country.

The ceremony, presided over by Prime Minister Yingluck Shinawatra, saw 4,000 kilogrammes (four tonnes) of drugs burned, including large hauls of heroin, speed pills and crystal methamphetamine – known as 'ice'.

Authorities said they have a further 24,000 kilos of confiscated drugs worth an estimated $2.2 billion awaiting destruction after they were seized in as yet unresolved drug cases.

“The government considers drugs suppression a key policy and burning the drugs is one measure to stop drugs from reaching the community,” Yingluck said at the event at an industrial estate in Ayutthaya province, north of Bangkok.

The drugs were incinerated in high temperature furnaces that authorities said would prevent drug fumes from rising into the air.

Since Yingluck's government took office in August there have been almost daily drug seizures as part of a wide crackdown on drug use and dealing.

More than 300,000 people have been treated in rehabilitation centres since October 2011, according to the public health ministry, adding half of them are aged between seven and 24 years.

The ministry estimates there are two million drug addicts across the country.

Thailand, along with other countries in the region, has seen a marked increase in seizures of methamphetamine as the world opiate trade declines.