A total of 150 police officers were deployed in Italy on Monday to hunt down gang members, the EU’s law enforcement agency, Europol, said in a statement.

Using the so-called “grandchild" trick, a gang member would phone an elderly person and psychologically manipulate them into believing the criminal was one of their hard-up relatives. The caller would then convince them to withdraw a large amount of cash, which would be picked up by an accomplice.

Five people were arrested in Italy, six in Poland and one in Switzerland, while police are still hunting for 20 suspects.

As part of the raids authorities also seized €1 million worth of assets, including real estate, precious stones, luxury watches and jewellery. The riches are thought to be the profits of more than 250 acts of fraud against the elderly, along with over 20 burglaries, Europol said.

Described as a “dangerous criminal network”, the gang allegedly targeted “polite and trusting” elderly people to con them out money.

Police in Genoa, north-west Italy, launched an investigation into the scam in 2010 and worked with Europol and Eurojust, the EU’s judicial cooperation unit.

In addition to Polish and Swiss authorities, those in Austria and Germany were also part of the operation, which involved wiretapping over 100 phones.

Despite crackdowns in recent years on "grandchild" fraudsters, Europol said there are still a “noteworthy” number of cases in Europe. The gangs move quickly across borders, making them harder for police forces to trace, while some elderly victims are too embarrassed to come forward when they realize they have been conned.