ROME - UN Secretary General Ban Ki-moon on Thursday called on the European Union to continue to work together to manage its worst migrant crisis since World War II, and praised the bloc's efforts to tackle what he described as a global phenomenon.

"I hope that the European Union, and also Italy, continues to show global solidarity," Ban said in an interview with Italian newspaper Corriere della Sera.

"This topic is important primarily for Europe, and I am encouraged to see the first agreements in the EU on reallocating refugees in various countries ... migration is now a global phenomenon."

Ban made the comments ahead of a summit of EU leaders due in Brussels on Thursday and Friday, the fourth in six months to be dominated by the more than half a million people who have come to Europe this year fleeing war and poverty in Africa, Asia, and the Middle East.

Italy sent a group of asylum seekers to Sweden last week, kicking off an EU-wide relocation programme aimed at easing the burden on border states.

Ban, who is due to address the parliament in Rome on Thursday, also urged Israelis and Palestinians to return to negotiations without delay, saying he had spoken to the leaders of both sides in recent days.

"An unsustainable situation is being created, an eruption of violence that gives cause for great alarm," Ban said. "I am trying to bring them back to talks."