The head of the U.N. refugee agency says Europe should boost efforts to integrate newcomers from places like Syria, Iraq and Afghanistan.

High Commissioner for Refugees Filippo Grandi says integration is "one of the great challenges" of the future.

Grandi was speaking to The Associated Press ahead of two summits in New York on refugees and migrants on Sept. 19-20, including one convened by U.S. President Barack Obama.

Grandi says Europe, which took in over 1 million refugees last year, also needs to handle possible rejections of asylum requests "with efficiency, so that people don't end up in limbo and disappear."

The UNHCR said "more thinking and more resources" should go into integration of refugees, which if done properly could "counter xenophobic tendencies, violent rejection and propaganda against foreigners."