Prime Minister Viktor Orbán said 80 percent of online criminal fraudsters "have a Ukrainian background, the members being Ukrainian and headquartered in Ukraine".

During an interview with public radio on Friday, the prime minister said the fraudsters did not conform to the typical image of mafiosi but were "refined and clever" and used sophisticated technology to achieve their ends. "Ukraine is a dangerous country," he declared.

PM Orbán said a call-center network had recently been uncovered in Ukraine targeting Hungarians. The fraudsters pretended to call from retail banks and swindled Hungarians out of their money, he added.

The prime minister also warned that Ukraine's European Union entry would make it "much easier" for criminals to "infiltrate the fabric of the EU".

"They would receive the same treatment as financial service providers in the EU, and it would be more difficult to act against them," he said. "Keeping Ukraine outside [the EU] is undoubtedly the only way forward," PM Orbán said.