Unless the migrant crisis in Europe is addressed properly there will be a surge of right-wing extremism across the continent, Frans Timmermans, European Commission vice-president, has warned.
r Timmermans also said that there needed to be better protection of the European Union's borders to deal with the hundreds of thousands of migrants fleeing war and poverty in the Middle East, Asia and Africa.
"We have to make sure that those countries where people arrive are better placed to make sure people are registered, that people who don't have the right to asylum are returned swiftly," he told BBC radio.
"If we're not able to tackle this issue, if we're not able to find sustainable solutions, you will see a surge of the extreme right across the European continent."
His comments came as German Chancellor Angela Merkel sought to reassure the public and politicians that the potential benefits resulting from the arrival of migrants and refugees far outweighs any dangers.
"The opportunities are much bigger than the risks, we just have to recognise and use them," she said.
But the German leader said the deal forced through to relocate 120,000 refugees among EU member states is far from being the only solution to tackle Europe's biggest migrant crisis since World War II.
"I am deeply convinced that what Europe needs is not just selective relocation of this kind, but much more a durable process for fairly distributing refugees among member states," she told the German parliament.
She said it was "a first step that has been taken, but we are still far from where we should be".
Seeking to reassure state governors, whom she was meeting with later in the day, Ms Merkel said Germany can meet the challenges.
"Who - if not we - has the strength to do so," Ms Merkel added.
Meanwhile, European Union leaders managed to agree early yesterday morning to boost border controls to manage the influx and to send €1bn to international agencies helping refugees at camps near their home countries.