The head of the U.N. refugee agency says a "positive relationship between the Western and the Muslim worlds" is essential to overcome refugee crises like those facing Europe.

Antonio Guterres is insisting on an urgent need to fight prejudice against Islam and reduce the lure of extremist ideologies.

The U.N. High Commissioner for Refugees said Monday that financing has fallen short to handle "mega-crises" like those in Iraq and Syria and other crises in South Sudan, Burundi, Yemen and Libya.

He said "the humanitarian system is financially broke" and 33 U.N. appeals for assistance for 82 million people are 42-percent funded.

Guterres noted Greece has faced more than 400,000 arrivals this year — a nine-fold increase from 2014 — mainly because of Syria's war.