Migrants attempt to break through Greece-Macedonia border

Hundreds of refugees on Tuesday tried to break through a border fence into Macedonia from Greece, where more than 7,000 people are stranded, as anger mounts over barriers to entry imposed on migrants flooding into Europe.

In a sign of deepening divisions within Europe, German Chancellor Angela Merkel lashed out at Austria and Balkan states for introducing tight limits on migrant entries, leaving Greece with a growing bottleneck as refugee boats continue to arrive from Turkey.

And Macedonian President Gjorge Ivanov warned that once Austria reaches its cap of a maximum 37,500 migrants transiting through this year, the refugee route through the Balkans will have to close.

At Idomeni on the frontier, Macedonian police fired tear gas as some 300 migrants forced their way through a Greek police cordon and raced towards a railway track between the two countries.

"Open the borders!" they shouted as a group of men used a metal signpost to bring down a section of barbed wire fencing, prompting police to fire volleys of tear gas and block them from crossing.

At least 30 people, many of them children, requested first aid in the stampede that ensued, the charity Doctors Without Borders (MSF) said. Authorities said a Macedonian policeman had also been hurt and had to be hospitalised.

The protest occurred several hours after Macedonia allowed just 300 Syrians and Iraqis to cross.

With Austria and Balkan states capping the numbers of migrants entering their soil, there has been a swift build-up along the Greece-Macedonia border with Athens warning that the number of people "trapped" could reach up to 70,000 in March.

The UN's rights chief criticised a "rising roar of xenophobia" towards migrants.

"To keep building higher walls against the flight of these desperate people is an act of cruelty and a delusion," Zeid Ra'ad Al Hussein said.

Amnesty International criticised the situation at Idomeni, branding it "the result of a shameful spate of discriminatory border closures".

As the bottleneck showed little sign of easing, Merkel slammed the restrictions and pointed the finger at Austria, whose clampdown on February 19 triggered a domino effect in the Balkans.

Greece must not be allowed to "plunge into chaos", she said.

The spate of border closures was sparked by Austria's announcement it would accept no more than 80 asylum claims per day and that a maximum of 3,200 migrants would be allowed to transit daily.