European Union leaders are set to hold a key summit in Brussels to discuss in more depth the body’s plans for dealing with refugees.

Leaders are to meet on Thursday in a summit that has been described as an opportunity for the continental bloc to return to core values even as Britain launched talks this week on leaving the union.

Summit chairman Donald Tusk wrote to leaders in an invitation letter that back-to-back defeats for far-right parties across Europe showed that the EU was passing the critical point.

"We are witnessing the return of the EU rather as a solution, not a problem," he said in the letter, adding that the no vote in France to the country’s main anti-refugee party showed that the EU was "slowly turning the corner."

French President Emmanuel Macron, who is making his first appearance at the EU summit in Brussels, also reiterated the need for the bloc to return to its main principles, apparently hitting out at states that have been reluctant to share the refugee burden that has been described as the most unprecedented in recent decades.

“Europe is not a supermarket. Europe is a common destiny. It gets weaker when it allows its principles to be rejected,” Macron said in an interview before the summit, adding, “European countries that don't respect the rules have to draw all the political consequences.”

Reports said that Macron would hold talks before the main meetings with leaders of Hungary, Poland, Slovakia and the Czech Republic -- countries that have challenged an EU scheme for the relocation of refugees. That would be a distraction from the tradition in an EU summit, where government leaders and heads of state usually meet in their political groupings to prepare for the main event.

A draft of their final summit statement pledges the EU leaders’ commitment to boost support and training programs for the Libyan coastguard in a bid to prevent more refugees from crossing the Mediterranean on unsafe boats in the hope of reaching Europe. The draft statement also underlines the need for the EU to send home refugees in greater numbers and more efficiently to “achieve real progress in return policy.”

The summit also comes days after EU representatives started official talks with Britain on how the country should leave the bloc throughout a process that is expected to last two years.