A British exit from the European Union could trigger similar moves by other member states in Eastern Europe, Luxembourg Foreign Minister Jean Asselborn said in a German newspaper interview published on Sunday.
Britain votes on June 23 on whether to stay in the 28-member bloc, a choice with far-reaching consequences for politics, the economy, defense and diplomacy on the continent.
"It cannot be ruled out that Brexit leads to a domino effect in Eastern Europe," Asselborn told Tagesspiegel am Sonntag.
It had been a "historic mistake" from Prime Minister David Cameron to even think about calling a referendum about Britain's membership of the European Union, Asselborn added.
Even if Britain should decide to stay in the EU, "this would not solve the problem that results from the negative attitude of the British towards the European Union", Asselborn said.