Polish Foreign Minister Witold Waszczykowski warned in a German newspaper that other countries could follow suit after Britons voted to leave the European Union.
"There is the danger of a domino effect," Waszczykowski told the online edition of German newspaper Die Welt.
He said it was therefore necessary to urgently think about what reforms were necessary in the EU, adding that the bloc needed to find new answers to economic challenges and migration as well as internal and external security.
