Ukrainian police have arrested four people suspected of running a network of fraudulent call centers that stole millions of euros from German citizens by luring them into fake cryptocurrency investments.

The arrests come as Kyiv steps up efforts to crack down on illegal call centers, some of which have allegedly operated under the protection of corrupt law enforcement officials.

In a statement Friday, Ukraine’s cyber police said the suspects operated call centers across the country, posing as financial advisers and persuading people in the European Union, particularly Germany, to invest in cryptocurrencies and stocks through fraudulent online platforms.

After gaining victims’ trust, the scammers helped them open cryptocurrency…