As frustrations boiled over at restrictions imposed on people moving through the Balkans, migrants trapped on the Greece-Macedonia border tore down a metal gate in the barbed wire fence.
A Reuters witness said Macedonian police fired several rounds of tear gas into the crowd and onto a railway line where other migrants sat refusing to move, demanding to cross into the country.
Greece raced to set up temporary accommodation for a build-up of thousands of migrants stranded in the country after Austria and countries along the Balkans migration route imposed restrictions on their borders, limiting the number of migrants able to cross.
German Chancellor Angela Merkel, facing the biggest test of her decade in power, defended her open-door policy for migrants on Sunday, rejecting any limit on the number of refugees allowed into her country despite divisions within her government over the issue.
"There are many conflicting interests in Europe," she told state broadcaster ARD.