In his opening speech at this year's World Economic Forum in Davos, German President Joachim Gauck said Europe's responsibility to help those fleeing war and conflict was a humanitarian one, but he also urged global leaders to not forget the economic benefits that come with migration.

"Migration has been an engine for progress and economic growth," Gauck said. "Most economists agree that labor migration has brought opportunities for increased prosperity. Not only for migrants, but also for the states that receive them."

He cited Germany's own history with migration, citing the once war-torn country's "economic miracle" that followed its reception of expatriated Germans after World War 2 as well as West Germany's reliance on foreign workers in the 1960s and '70s.

But he also said he was aware that Europe cannot take in an unlimited number of refugees, lest countries become overwhelmed and fail to integrate those migrants who have already arrived.

Not 'per se unethical'

On this, he said limiting the number of refugees allowed to enter Europe would not necessarily be the wrong thing to do.

"A cap is not per se unethical: A cap could help to maintain acceptance," Gauck said. "Without acceptance, a society cannot be open and receptive."

Gauck also noted that the debate in Germany and Europe over asylum seekers has changed since the New Year's Eve sexual assaults in Cologne, which raised questions about the willingness of some newcomers to respect the rule of law and the role of women in Western society.

He warned that if efforts to integrate new arrivals into European society failed, or if authorities were unable to guarantee people's safety - a nod to the inability of police to help some victims in Cologne on New Year's - then European citizens and refugees alike could become disenchanted.

Gauck's speech echoed urgings from the International Monetary Fund to open job markets quickly to refugees. In a new study to be released this week in Davos, the IMF said the short-term impact of the surge in refugees to Europe should be beneficial to economic growth, but it noted that any long-term benefits would depend on efforts to integrate them.