Almost 2 tonnes of cocaine with a market value of more than 400 million euros ($440 million) were found floating at sea off eastern Sicily, in what Italy's tax and customs police on Monday called a record seizure.

The drugs were stored in about 70 waterproof packages, carefully sealed, held together by fishermen's nets and equipped with a luminous signalling device, the Guardia di Finanza said in a statement.

The "peculiar packaging methods and the presence of a luminous device to allow tracking" suggest the haul was dumped at sea by a cargo ship in order for it to be recovered later, the statement added.

Monday's seizure compared with the 20 tonnes of cocaine that Italian police managed to intercept over the whole of 2021, its anti-drugs unit said in figures released last June, stressing that was the highest yearly amount on record.

Cocaine seizures increased more than five-fold from 3.6 tonnes in 2018, police noted at the time, describing Italy as a key transit route for the cocaine trade, and where Balkan criminal gangs were consolidating their positions.

"Congratulations to the Guardia di Finanza for this extraordinary operation: (I am) against all drugs and for life, no matter what", Deputy Prime Minister and Infrastructure Minister Matteo Salvini tweeted on Monday.