National borders are the "worst invention ever" according to European Commission president Jean-Claude Juncker.
His comments come as European countries are to discuss tightening their borders in response to the migrant crisis that is overwhelming some countries.
Speaking to the European Forum Alpbach, Juncker said: "Borders are the worst invention ever made by politicians."
He added that solidarity must be given to refugees and their children.
But his remarks were "not something the Prime Minister would agree with", Theresa May's spokesperson said.
In the same interview, Juncker said Brexit was not a pretty moment and one which the EU must overcome.
He said: "In the concentration of globalisation and European problems, we must not lose our way."
German chancellor Angela Merkel, French president Francois Hollande and Italy's prime minister Matteo Renzi are meeting on the Italian island of Ventotene for talks on Monday to discuss the way forward for the EU in the wake of the UK's historic decision to leave the EU.