The Hungarian riot police fired tear gas and water cannon on Wednesday at crowds of refugees and migrants desperate to cross the border from Serbia. Others carved out a new route and headed for Croatia.
Tensions boiled over at the flashpoint Horgos-Roszke crossing, where hundreds of furious people tore down the wire meshing separating them from Hungarian territory, and police clashed for hours with migrants, some of whom threw stones, sticks and plastic bottles.
The unrest left 14 Hungarian police officers injured, authorities said.
Refugees save themselves from tear gas by covering their faces during clashes with the Hungarian riot police at the Hungarian border with Serbia near the town of Horgos on Wednesday. (AFP Photo)
Serbia lodged a formal protest with Hungary over the use of tear gas on its territory, and interior minister Nebojsa Stefanovic said police reinforcements were being sent to the Serbian side of the border to help calm tensions.
UN chief Ban Ki-moon said he was "shocked" by Budapest's actions, as hundreds of people fleeing war and misery, many of them Syrians,, remained stranded at Hungary's newly fenced-off border.
"We want to leave! We want to leave to Germany!" cried one French-speaking man at a migrants' protest at the border through a megaphone.
Crowds who managed to overrun police lines and break through the fence in the Hungarian town of Roszke did not take advantage to run deeper into the central European country's territory however, apparently wanting instead to show their frustration after Budapest sealed the border on Tuesday, an AFP correspondent said.
In the chaos, at least four children were separated from their families and apparently taken by police to a nearby border control building, rights group Amnesty International said.
Migrants try to remove the gates at the Hungarian border with Serbia near the town of Horgos on Wednesday. (AFP Photo)
Gyorgy Bakondi, Hungarian PM Viktor Orban's chief advisor, said the tough response came an hour after the migrants had issued an "ultimatum" to police, demanding to be let through.
Earlier on Wednesday, migrants desperate to find new ways to eastern Europe were granted access by Croatia. By Wednesday evening, some 1,300 men, women and children had entered the Balkan nation, the interior minister said.