Firefighters prepare to distinguish fire after burning seized drugs at an event to mark International Day against Drug Abuse and Illicit Trafficking, outside Yangon, Myanmar June 26, 2017. REUTERS

Officials in Myanmar and Thailand burned illegal narcotics worth more than $800 million on Monday to mark the UN day against drug abuse and trafficking.

The move came even as authorities struggle to stem the flood of illicit drugs in the region, with Thailand's justice minister last year saying the country's war on drugs was failing.

In Thailand's Ayutthaya province, more than 9 tonnes of drugs with a street value of over 20 billion baht ($590 million) went up in smoke including methamphetamines, known locally as "yaba" or "crazy drug", according to police.

"Currently, we are able to take down a lot of networks, including ... transnational networks bringing drugs into Thailand ... to be shipped to Malaysia and other countries," Sirinya Sitthichai, Secretary-General of the Office of Narcotics Control Board, told reporters in Ayutthaya.

In neighbouring Myanmar, the police said they destroyed confiscated drugs worth around $217 million.

Myanmar remains one of the world's largest producers of illicit drugs, including opium, heroin and methamphetamines. Those narcotics are often smuggled into China.

Last year, law makers in Myanmar voiced disappointment over the country's lacklustre efforts to tackle the drug problem.

The market for methamphetamines has been growing in Southeast Asia, the United Nations has said. It estimates that Southeast Asia's trade in heroin and methamphetamine was worth $31 billion in 2013.