Refugees protest as bottleneck builds

Stranded migrants lay with their children on rail tracks at Greece's northern border on Sunday, demanding to be allowed to continue their journey, as Germany warned that Europe cannot let the country "plunge into chaos".

German Chancellor Angela Merkel was speaking as Athens said that the number of migrants trapped in Greece could triple after Balkan countries announced a daily cap on migrant arrivals.

Tensions between European nations worst affected by the migrant crisis are running high, with Austria's Chancellor Werner Faymann accusing Greece of "behaving like a travel agency" for migrants hoping to start new lives elsewhere in Europe.