Police tracked three suspect containers to the port of Salerno, in Campania, and found 84 million pills with a market value of $AUD1.6 billion inside machinery and paper cylinders for industrial use, the Guardia di Finanza said in a statement on Wednesday.

Investigators said the bust is the largest drug haul in the world in terms of both value and quantity.

They hypothesised that amphetamine production in Europe has been hampered by the pandemic lockdown, and so drug traffickers may have turned to Syria-based producers to fill the market.

The amphetamines were labelled “captagon”, the street name for a drug whose chemical base was originally fenethylline.

However, according to the United Nations Office on Drugs and Crime World Drugs Report 2020 what drug organisations call “captagon” these days is usually a mixture of amphetamine, caffeine and other substances.

It’s unclear whether the drugs seized in Italy were fenethylline-based or a substitute.

The imitation captagon is popular in the Middle East, and widespread in war-torn areas such as Syria, where conflict has fuelled demand and created opportunities for producers.

Production was initially concentrated in Lebanon and IS sells it to finance its activities, police said in a statement.

The statement said captagon was known as the “drug of the Jihad” after being found in militant hideouts, including one used by the Islamists who killed 90 people at the Bataclan theatre in Paris in 2015.

Police said they were investigating if Naples-based Camorra organised crime clans might have ordered the huge shipment for international sale.

Two weeks earlier, a much smaller shipment of the drug was seized in Salerno’s port in a shipment of clothing.

Police believe the drugs were intended for distribution in Europe by various organised crime groups.

In 2019, Greek authorities claimed to have made the biggest amphetamines bust of all time after seizing 5.25 tonnes of captagon, also produced in Syria.