Army chief Apirat Kongsompong vows to dismiss Internal Security Operations Command (Isoc) officers found guilty of drug offences.
The general, also deputy chief of Isoc, said he believed crackdowns on drug trafficking gangs alone may not be enough to root out the drug problem.
There is a need to also look at the command, which is a key agency in the state's anti-drug campaign, and find flaws in the implementation of drug busting measures, for which some Isoc officers are to blame.
He spoke of the urgency to launch effective measures to combat illicit drugs during a meeting on Monday with chiefs of Isoc units in 77 provinces, including Bangkok. The meeting discussed the adoption of a zero tolerance policy on corruption among any members attached to the agency tasked to help fight the illicit drug trade.
Isoc officials who become involved with the drug trade will be dismissed because it is a serious offence that is often related to the acquisition of illegal weapons, said Isoc spokesman Maj Gen Thanathip Sawangsaeng, quoting Gen Apirat.
Maj Gen Thanathip said some armed minority groups in neighbouring countries produce and sell drugs for money, which is then used to finance the purchase of weapons.
This prompts Thai authorities to keep an eye on the activities of cargo and people along the border to prevent drug smuggling.
Gen Apirat stressed in the meeting that Isoc must cooperate with other agencies to tackle transnational drug trafficking.
"Drugs must be stopped at the borders," Maj Gen Thanathip said, referring to Gen Apirat's policy.
Authorities must also intensify searches at roadside checkpoints during the holidays as some motorists may secretly be carrying crystal methamphetamine, speed pills and marijuana.
Gen Apirat also touched on the Isoc's role in next year's election.
The agency is duty bound to help maintain order during the poll. The kind of assistance it will lend to the Election Commission will be decided by the regulator, he said.
At present, Isoc units are working closely with the provincial governors on all security issues.
Isoc is waiting for a new national security policy from Prime Minister Prayut Chan-o-cha -- the Isoc chief -- next month.
That will provide Isoc with clearer working guidelines," Maj Gen Thanathip said.