Greece has seized drugs worth more than 100 million euros ($113 million) after intercepting a Syrian ship sailing for Libya, Reuters reported the coast guard as saying on Friday.
Officials found about six tonnes of processed cannabis and 3 million super-strength "Captagon" amphetamine pills hidden aboard the Syrian-flagged "Noka", it said in a statement.
The freighter, with a crew of 11, was en route from the Syrian port of Latakia to Benghazi when it was intercepted by Greek authorities off the southeastern coast of Crete on December 5.
The Noka was escorted to Heraklion port on the Greek island on December 8, where the authorities unloaded its entire cargo.
The drugs were found under false floors in eight containers, hidden between layers of coffee, spices and wood shavings.
Syria became a major amphetamines exporter and consumer as the trauma of the country's civil war fuelled demand and the breakdown in order created opportunity for producers.
Captagon was said to be a fund-raising tool and stimulant for militants. The government now controls most of the country and Daesh is close to defeat.
Greek authorities have impounded the vessel and its contents. The crew have been arrested and will appear before a public prosecutor on Saturday.
Scientists say Captagon is a super-boosted amphetamine with unique chemical complexities allowing it to induce potent psychoactive effects far more rapidly than amphetamines alone.