Italian, Belgian and German police arrested 31 suspects on Monday in a sting targeting a cocaine smuggling network by the 'Ndrangheta mafia on the continent, Europol said.

More than 840 officers took part in "joint action day" raids in which 53 searches were carried out, resulting in the seizure of cash and other assets valued at 3.8 million euros (US$4.1 million).

The operation follows a previous probe between 2013 and 2018 by Italian authorities into the mafia group's activities.

"The suspects allegedly continued to use the existing and well-established network to transport mainly cocaine from South America to Germany and Italy via several European ports," said Europol, which coordinated the operation with its twin judicial agency Eurojust.

"To this end, the organised crime group set up businesses in Germany to facilitate the drug smuggling. To cover its drug transports, the group used international companies trading in cars and food," Europol said.

Eighteen suspects were arrested in Italy, eight in Belgium and five in Germany, Europol said.

Based mainly out of Italy's rural southern Calabria region, the 'Ndrangheta mafia controls the bulk of the cocaine flow into Europe.

Now extending far beyond its Calabrian rural roots, it now operates in over 40 countries around the world.

Besides its main source of wealth, drug trafficking, the 'Ndrangheta is involved in money laundering, extortion, trafficking of illegal waste and other criminal activities, using shell companies to invest illegal gains in the legitimate economy worldwide.

Early last month, police across Europe staged a vast coordinated raid against the group, arresting some 132 people. (AFP)