Four drug smugglers have been killed on the Jordanian-Syrian border, Jordan’s army said on Sunday.
The army said border guards attacked the smugglers, some of whom were armed, after they entered the country from Syria.
“Fast response mechanised units dealt with these groups,” its statement said.
The army said 637,000 pills of Captagon were seized.
The Jordanian border is the main transit point for Captagon, an amphetamine derivative that is one of the region’s most widely used recreational drugs.
Pro-Iranian militias are involved in the tablets’ manufacture and most are made in areas of Syria held by the Assad regime.
Most are smuggled to wealthier Arab countries for sale, the security forces have said.
But some are used in Jordan. This year, authorities in Amman uncovered a Captagon manufacturing and export cartel in the kingdom.
Jordanian security forces say billions of dollars' worth of the pills are trafficked across the Syrian-Jordanian border each year.
In the past three years, the border has become a geopolitical battleground in which Jordan is vying for influence.
Saudi Arabia and Jordan have different opinions on how the drug problem should be handled.
Saudi officials regard the drug smuggling as part of an Iranian drive to undermine their country's national security and the kingdom has opposed Arab calls to rehabilitate the Assad regime on a region-wide scale.
The rapid rise in Captagon smuggling factored in Jordanian policy in the past two years of accommodating the government of Bashar Al Assad in the hope of securing regime co-operation to curb the drug trade.
Late last year, Moscow, which has troops in Syrian regime areas near the border with Jordan, arranged talks between Amman and Damascus. The US, Jordan’s main donor and chief ally, gave mixed signals.
Jordan supported the 2005 Russian intervention that all but neutralised threats by the Syrian opposition to encroach on President Assad’s seat in power in Damascus.
Russian forces also secured areas near the Mediterranean coast inhabited by members of his Alawite minority, which has dominated power in Syria for the past 59 years.
But Jordan's King Abdullah told the Hoover Institute while on a visit to the US this month that he expects Russia’s focus on its invasion of Ukraine to tilt the balance in Syria in favour of Iran. Teheran supports an array of militias in Syria broadly overseen by Hezbollah.
“That vacuum will be filled by the Iranians and their proxies, so unfortunately we are looking at an escalation of problems on our borders,” the king said.
“We're seeing border attacks on regular basis and we know who is behind that.”