The European Commission is “extremely concerned” about member states offering citizenship to rich investors, Vera Jourova, the commissioner for justice, consumers and gender equality, has warned.

A growing number of EU countries are issuing passports to third-country nationals if they have invested large sums in the country, Czech politician Jourova said to German-language newspaper Die Welt.

She said that the commission is “extremely concerned” that these so-called ‘golden passports’ are a security threat, as they give recipients all of the rights of EU citizens and means they can move throughout the bloc unhindered.

“The EU must not become a safe haven for criminals, corruption and dirty money,” Jourova told the German paper. “Some member states must do more to ensure citizenship is not awarded to criminals.

“We don’t want any Trojan horses in the EU.”

Jourova said that each country’s practices in granting citizenship to people from outside the European Union will be examined.

This will likely lead to tougher guidelines for member states to guarantee that candidates for citizenship won’t damage the union, she said.

EU countries currently offering citizenship or visas in exchange for investment are: Austria, Belgium, Bulgaria, Cyprus, Greece, Latvia, Lithuania, Malta, Portugal and Spain.

According to law firm Henley & Partners, Moldova and Montenegro have unveiled plans to launch citizenship by investment schemes.

The UK offers investor visas but, as it is not part of the Schengen visa-free travel area, this does not allow unrestricted travel across the EU.