The European Union's most powerful official says increasing border control is not how Europe should deal with the continuing challenge of the refugee crisis.

Speaking at the European Forum Alpbach on Monday, Jean-Claude Juncker called on Europe to show "solidarity" with refugees and described borders as the "worst invention" ever produced by politicians.

"We have to fight against nationalism," said Juncker, who is the president of the European Commission, the EU's executive branch. "We have the duty not to follow populists but to block the avenue of populists."

He added: "Borders are the worst invention ever made by politicians... In the concentration of globalisation and European problems, we must not lose our way."

The Forum is an event which takes place in Austria where speakers of different nationalities from multiple fields are invited to give lectures on a range of topics, many of which are political.

Juncker's remarks come at a time when public angst about immigration and security across the continent is high in light of recent terrorist attacks in France, Belgium, and Germany.

A Pew Research Center survey published last month revealed that in eight of the 10 EU member states surveyed, more than half of people feared that the continued influx of refugees would increase the likelihood of terrorism in their country. At least one of the perpetrators behind the attacks in Paris in November made into the EU by posing as a refugee and using fake documentation.

Some British diplomats were stunned that the European Commission President appeared to be advocating an open borders policy. "Theresa May would certainly not agree with him," an unnamed British official told the Evening Standard.

The President was speaking in Austria on the same day that German chancellor Angela Merkel was due to meet with French leader François Hollande and Italian Prime Minister Matteo Renzi and discuss issues including migration.

The three leaders were also set to discuss how the 28-nation bloc should move forward following Britain's vote to leave the EU in the June referendum.