EU cannot stem refugee crisis without Turkey, says Merkel

German Chancellor Angela Merkel said Thursday Europe had no chance of overcoming its biggest refugee crisis without cooperation with Turkey and called for a crackdown on human smuggling off its coast.

"We cannot organise or stem the refugee movements without working with Turkey," she said, speaking hours ahead of a European Union [EU] summit.

She acknowledged Turkey was playing host to millions of Syrian refugees, an effort that she said European partners must support.

Europe needs to show solidarity, anything else would be a failure - German Chancellor Angela Merkel

But it was also "unacceptable that the tiny sea crossing" between Turkey and Greece, both NATO members, was being controlled by human traffickers, said Merkel.

The chancellor travels to Ankara on Sunday for talks with President Recep Tayyip Erdogan.

Underlining the scale of the migrant crisis facing Europe, Merkel told German lawmakers that "it is not an exaggeration to describe this task as a historic test for Europe".

As a result, "Europe needs to show solidarity, anything else would be a failure," she warned.

In a retort to critics of her open door policy to those fleeing war and persecution, Merkel said slamming the door shut "in the 21st century of the Internet era is an illusion".

Germany itself is expecting to receive between 800,000 and one million asylum seekers this year, and disgruntled local authorities who are struggling to cope with the sudden influx surge have been openly critical of Merkel's policy.

But the chancellor has repeatedly said it was impossible to immediately end the influx, given that the war in Syria, one of the root causes of the crisis,  shows no signs of being resolved.