German Chancellor Angela Merkel urged Europe to cooperate with Turkey to tackle the region's worst refugee crisis since World War II. Merkel’s comments came Thursday, ahead of a summit in Brussels to discuss efforts to ease the crisis.

"Without a doubt Turkey plays a key role in this situation," Merkel reportedly said in a speech to the Bundestag lower house of parliament Thursday. "Most war refugees that come to Europe travel via Turkey. We won't be able to order and stem the refugee movement without working together with Turkey.”

At least 2 million Syrian refugees currently live in Turkey and the country has made strides to accommodate them. Turkey has reportedly been one of the main departure points for those trying to enter Europe.

Merkel said that Turkey must be provided with more support in caring for the refugees and providing them with humanitarian aid, along with ways to help secure borders and fight criminal smuggling rings, according to Reuters.

Merkel is scheduled to visit Turkey on Sunday to hold talks with President Recep Tayyip Erdogan and Prime Minister Ahmet Davutoglu.

"Treaties will be adhered to, and the EU's negotiations with Turkey conducted without pre-judging,” Merkel said about Turkey's application to join the European Union.

Meanwhile, on Thursday, United Nations Secretary-General Ban Ki-moon called on EU leaders to continue to work together to handle the refugee influx as more than half a million people, fleeing war and poverty in Africa, Asia, and the Middle East, reached Europe this year.

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