A total of 261 suspects from West Africa have been arrested in 221 cases of drug cases after a narcotics crackdown dubbed the "Airport Interdiction Task Force (AITF)".
Seized along with the arrests of these suspects were 417 kilogrammes of cocaine and 198kg of crystal methamphetamine, said Sirinya Sitdhichai, secretary-general of the Office of the Narcotics Control Board (ONCB).
These were accumulated figures recorded since the AITF began its operation in 2012, he said.
The common drug-trafficking route starts in South America such as Colombia, Peru, Argentina and Brazil, he said, adding the drugs were normally brought into Thailand through the Middle East.
However, after Thailand began implementing tougher screening measures at its international airports, the drug-trafficking route was then diverted to neighbouring countries first before eventually entering Thailand, he said.
After reaching the neighbouring countries, the traffickers managed to get into Thailand through the border areas, he said.
Late last year, Japanese authorities began notifying their Thai counterparts about a surge in the amount of drugs smuggled into Japan from Thailand, he said.
The notification came along with a request for help with investigating a West African drug network believed to be behind the exploitation of many Thai women to use them as drug mules destined for Japan, he said.
In order to deceive customs, Thai or Asian women were also hired to marry or accompany male smugglers.
The Thai-Japanese collaboration led to the arrests of 27 Thai women recently, he said. Since April last year, 26 Thai nationals have been detained in 23 drug cases upon their arrival at Japan's airports, he said, adding that the combined amount of crystal meth seized in these cases was 27.6kg.
Three more suspects have been intercepted since then at Don Mueang airport in two cases involving the same class of drugs.