On Wednesday, there were chaotic scenes near the Hungarian town of Horgos, with fires burning and police vehicles and ambulances arriving on the Serbian side of the border, across from massed ranks of riot police on the other side. The firing of tear gas and water cannon created a stampede of migrants away from the border.

UN Secretary General Ban Ki-moon has said he is "shocked" after Hungarian police fired tear gas and water cannon to force migrants back from its border.Mr Ban said such treatment of asylum seekers was "unacceptable".Serbian Prime Minister Aleksandar Vucic als accused Hungary of being "brutal and "non-European".

Hungary defended its action, saying that 20 police officers were injured as migrants tried to break through a gate, and a spokesman accused migrants of using children as "human shields".At least two migrants were also injured, Hungarian and Serbian officials said.Hungary closed its entire border with Serbia on Tuesday after making it illegal to enter the country or damage the border fence.Several people received treatment from the Serbian ambulance service, some suffering the effects of tear gas.