The 31-year-old suspect "had been professionally smuggling captagon to Arab countries for around six years," the Internal Security Forces said, without naming the man.
He confessed to carrying out "12 smuggling operations to Egypt, Qatar, Yemen, the United Arab Emirates, Sudan and Saudi Arabia," it said in a statement.
He was "one of the most prominent of those involved" in smuggling captagon from Lebanon to the Gulf, the statement said.
He was arrested in the Bekaa Valley in a bust coordinated with Saudi Arabia's Directorate of Narcotics Control, it said.
Four other members of the same smuggling network - two Lebanese and two Syrians - were also arrested, according to the statement.
Captagon is an amphetamine manufactured in Lebanon and probably also in Syria and Iraq, mainly for consumption in Saudi Arabia, according to the French Observatory for Drugs and Drug Addiction (OFDT).
It is also one of the most commonly used drugs in the Syrian war, where fighters say it helps them stay awake for days and numbs their senses, giving them stamina for long battles and allowing them to kill with abandon.
Lebanon has previously stopped several shipments of the drug to Gulf countries, including Saudi Arabia.
In May, it arrested a Saudi man at Beirut airport carrying about 10 kilogrammes of the drug.
In April, it seized more than 800,000 pills worth around $12 million in a bust coordinated with Saudi authorities.
In one of the country's largest busts, Lebanon arrested a Saudi prince and four other Saudi nationals in October 2015 for attempting to smuggle out nearly two tonnes of captagon via Beirut's airport.
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