As EU leaders prepare to hold an emergency summit next week, crowds of migrants crossing from Serbia have broken through riot police lines on the Croatian border at Tovarnik.

Croatia is struggling to deal with at least 6,000 arrivals since Wednesday morning after Hungary closed its border with Serbia, blocking the previous route into the European Union.

Croatian officials say migrants must apply for asylum there or be treated as illegal immigrants.

EU leaders will hold an emergency summit next week to discuss the crisis.