Brussels - European Council President Donald Tusk challenged Germany's migration policy on Thursday, in an interview in which he called for member states to abide by asylum rules and downplayed a Berlin-cherished plan for the sharing of refugees.Europe is struggling to get a handle on the steady flow of migrants and asylum seekers that have sought to reach its shores this year. More than 900 000 have arrived by land and sea, according to the International Organisation for Migration.Tusk acknowledged in his interview that applying the EU rules is difficult, but also warned that it was "dangerous" for some EU leaders to argue that "this wave of migrants is too big to stop" - in what was interpreted as a swipe at Berlin.Berlin at one point said that it would no longer turn back Syrians, despite provisions in EU law for asylum requests to be registered in the first member states that a person sets foot in.Germany has been the prime destination for migrants, leading to chaotic scenes as they struggle to cross the frontiers into Europe's biggest economy."[T]his wave of migrants is too big not to stop them," Tusk told the newspapers, which included Britain's The Guardian, Germany's Süddeutsche Zeitung and France's Le Figaro."No one is ready today to receive these kinds of numbers, including Germany," he added.International protection Germany is keen to spread the burden of processing asylum applications and has been pushing for the European Union to establish a permanent redistribution scheme that would allow migrants qualifying for international protection to be shared out among member states.But Tusk downplayed the prospects of the measure."There is no majority in Europe to win when it comes to resettlement or the next phase of [refugee] relocation," he said, adding that "many more countries" beyond traditional eastern and central European holdouts are opposed to the idea.Tusk instead reiterated calls for the EU's external borders to be better controlled and suggested that migrants should not be allowed to move freely for up to 18 months so that they can undergo security and other screenings."This control on our external borders and procedures inside the frontline countries - but also in some other countries - is something that will reduce this readiness to go to Europe," he said. "Today access to Europe is, simply speaking, too easy."Tusk also dismissed suggestions that Syrians make up most of the migrant flow headed towards Europe, putting their share at "only ... 28 to 30% of the influx."The UN Refugee Agency, however, estimates that Syrians made up more than 50% of this year's migrant arrivals by sea.The overwhelming majority of Syrians qualify for asylum in the EU as refugees fleeing civil war.