There are concerns that without a coordinated approach by the bloc’s 27 members, the Schengen free-travel zone could be disrupted by the introduction of de facto land borders.

Italy said on Tuesday that from Dec 16 it would require all travellers from EU countries to present a negative test on arrival, even if they are vaccinated.

Portugal, Ireland and Greece have also introduced requirements for negative tests for anyone arriving in their countries.

Xavier Bettel, Luxembourg’s prime minister, has warned new internal restrictions would undermine the vaccination drive.

“If you make no difference between vaccinated, not vaccinated people, because they need a PCR test, I think it’s the wrong idea,” he said. “It’s not a position I will defend. It’s a national decision, but for me it’s a common problem.”

Summit conclusions agreed by EU leaders said any restrictions should be coordinated and should not “disproportionately hamper free movement between member states”.