Mexican riot police use water cannons and tear gas against striking teachers

Mexican riot police have cracked down on the strongest challenge yet to President Enrique Pena Nieto's reform programme, sweeping thousands of striking teachers out of Mexico City's main square with tear gas and water cannons.

Workers moved swiftly late on Friday to demolish the half-burnt protest camp where striking teachers had camped out for weeks in a bid to block Pena Nieto's education reforms, which are aimed at introducing teacher evaluations and reducing union discretion in hiring.

But while Pena Nieto can now use the vast main square known as the Zocalo to hold the country's traditional Independence Day celebration today, it's unknown whether the crackdown will heighten opposition to his energy and tax reforms.

Moving against the striking teachers may have set the tone for any future protests of Pena Nieto's proposals for a steep tax hike and profits-sharing contracts for private companies in the state-owned oil industry. Both the tax and oil proposals have drawn howls of opposition.

Friday's raid by thousands of police against the teachers was a dramatic reassertion of state authority after weeks of near-constant disruption in the centre of one of the world's largest cities. The teachers have marched through the capital at least 15 times over the last two months.

Authorities did not immediately report any injuries. Federal police chief Manuel Mondragon said 31 demonstrators were arrested, none of them teachers.