ATHENS, Greece — Greek authorities say they have seized more than five tons of the synthetic drug known as Captagon, which they say is the largest amount of the drug ever seized globally.

Greece’s financial crimes squad said Friday the drug, which is popular in the Arab world and known to be used by some jihadis before carrying out attacks, was found in three containers originating in Syria.

The drugs, consisting of more than 33 million pills, had a street value of $660 million, the financial crimes squad said in a statement, adding that investigations were ongoing to find those involved in the smuggling as well as whether the shipment was heading to China.

Authorities said it took 20 employees a week to complete the search of the containers.