European Union and Italian authorities are investigating suspected wide-scale tax fraud by Chinese criminal gangs importing goods via Greece's largest port of Piraeus, a trade gateway between China and Europe, officials said.

"The VAT is completely evaded, with enormous damage to the national tax authorities and to the community," Fabio Botto, of the Italian Central Anti-fraud Office's special investigative unit, said in an interview.

He said the suspected scam at Piraeus, part of China's vast "Belt and Road" infrastructure project, had cost Italy tens of millions of euros in unpaid value-added taxes (VAT), though the total could be far higher as the investigation is not yet over.