Thousands more migrants entered Austria over the weekend as European leaders are set to push for a unified response to the crisis, BBC News reports.

Austrian authorities are expecting more arrivals from Hungary on Monday, September 21.

Foreign ministers from four eastern European countries are holding talks on the crisis later, kicking off a week of intense diplomatic activity.

EU interior ministers are to meet on Tuesday, with leaders convening for an extraordinary summit the following day. The crisis has exposed deep divisions among European states.

French President Francois Hollande has said in the EU, "no-one can be exempt" from taking in people with the right to asylum, while European Council President Donald Tusk said that the EU should help Syrian refugees to "a better life closer to their homes".

But at the meeting due later on Monday, the foreign ministers from Hungary, Poland, Slovakia and the Czech Republic are expected to reaffirm their opposition to Germany's call for a more even distribution of migrants.

German chancellor Angela Merkel called on her peers on Sunday to accept joint responsibility, Reuters reports.

"Germany is willing to help. But it is not just a German challenge, but one for all of Europe," Merkel told a gathering of trade unionists. "Europe must act together and take on responsibility. Germany can't shoulder this task alone."