French riot police have sprayed migrants with a chemical irritant as they tried to storm the Channel Tunnel.

The migrants, who broke down several security fences late on Saturday night, were forced to retreat by riot police as they attempted to breach the final fence near the entrance of the 50-kilometre tunnel under the English Channel.

The migrants, estimated to number around 200, faced off for close to an hour with security forces, chanting slogans including: "Open the border" and "We are not animals."

Thousands of migrants have been scaling fences near the tunnel in recent weeks, trying to hop on freight trains or trucks destined for Britain. One man was fatally crushed by a truck.

Most of the migrants have fled war, dictatorship and poverty in Africa and the Middle East, entering Europe Greece or Italy before heading north. Many think Britain offers the best prospects, because of the English language, welfare benefits and the perceived ease of getting a job.

The migrant activity at the tunnel - combined with a series of strikes by French ferry workers - have disrupted freight and passenger traffic, and spurred both governments to promise higher fences, more surveillance cameras and extra security guards.

British and French interior ministers said the nightly attempts to reach Britain are part of a "global migration crisis" that needs an international solution.

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