Greek authorities have confiscated a huge shipment of painkillers in the country's biggest port after they were informed the drugs were destined for Islamic State group fighters.

The financial crimes squad said Friday that more than 26 million pills were found in a container registered as containing linen goods. It said Greek authorities received assistance from the U.S. Drug Enforcement Administration.

An official involved in the operation said the drugs were shipped from India to Piraeus in Greece, and had been due to be transported in another freighter to Libya.

He said Greece received information from foreign services that the Libyan company due to receive them was a conduit for the Islamic State group, which would either use the drugs for its fighters or sell them for a profit.