Malaysian customs authorities thanked Saudi Arabia for its assistance in stopping a $1.26 billion drug shipment – the largest the country has made. Authorities found 94.8 million pills of Captagon, a popular but illegal amphetamine, at Klang Port on March 15. The tip-off from Saudi Arabia's Ministry of Interior led to the bust, Malaysia's head of customs, Datuk Sri Abdul Qadir, said on Wednesday. He described it as the "biggest success ever". Mr Abdul Qadir said the operation was a joint effort between the customs administration in Malaysia and the general directorate for narcotics control at the kingdom's interior ministry. The 16 tonnes of drugs were hidden inside the wheels of three containers that arrived at the port from a Middle Eastern country. "We believe we have crippled the activities of an international drug cartel,” Mr Abdul Qadir said. “Once the goods arrive in this country, they will be shipped to a third country before being sent back to their country of origin. This is the modus operandi used by international [drug] syndicates," he said. He thanked Saudi Arabia’s Ministry of Interior for the tip-off, but said no arrests had been made yet. The case is being investigated under Malaysia's Dangerous Drugs Act, under which a guilty verdict could lead to a death sentence. Captagon is known in the Middle East as the drug of partygoers and militants, rising to prominence in the Syrian war as a way to boost fighters on the battlefield. Syria is a major producer of the drug, which is smuggled into neighbouring countries and hidden by cartels in containers and shipped overseas – particularly to the Gulf. A million Captagon pills were seized at Beirut airport in March after a joint effort by Saudi Arabia and Lebanon.