Guardia di Finanza police colonel Francesco Ruis told Reuters a distinctive aspect of the case was the connection created between organisations like the 'Ndrangheta and Chinese entities providing financial services.

Ruis, who led the latest investigation in Rome, said the figure of more than 50 million euros in tracked financial movements did not give the true dimensions of the affair.

"This is what we have tracked from 2020 to 2022, but investigations cannot trace all operations. It's like doing a stakeout, you see 20% of what happens", he said.

Guardia di Finanza police said in a statement they had arrested 33 people, including seven Chinese nationals, in Rome and in other six Italian towns on charges of organised criminal conspiracy for drug trafficking and money laundering.

They also seized around 10 million euro in cash from so-called 'money mules', who were in charge of transferring money abroad, the statement said.

Several recent investigations have shown how drugs cartels in Italy are increasingly using shadow networks of unlicensed Chinese money brokers to conceal cross-border payments.

The transfer method, often referred to by the Chinese term fei qian or fei chien, meaning flying money, involves depositing a sum with a money broker in Italy while another agent in the network elsewhere in the world pays the equivalent amount to the intended recipient.

The money laundering at the centre of the latest case took place at Chinese import-export businesses of clothing and fashion accessories in the Esquilino district of the Italian capital.

These acted as collection centres for the money of illicit origin, which was eventually transferred anonymously and untraceably to China.

The fie chien method does not involve the physical transfer of money from the customer, who buys the drug shipment, to the supplier, who sells it. But China was the final destination for the cash, police said.

"The deals between the two Chinese brokers took place through triangulations and fictitious business transactions in China, while the cash travelled by plane to China using the so-called money mules," Ruis said.

The investigation was helped by accessing encrypted chats on a platform that was dismantled in 2021 by a Europol Joint Investigation Team, the statement said.

($1 = 0.9524 euros)

(Reporting by Emilio Parodi, editing by Crispian Balmer, William Maclean)

By Emilio Parodi