LONDON - Hundreds of protesters clashed with police in front of the British parliament in central London on Thursday ahead of a vote on university tuition fees which will test the strength of the coalition government.

Demonstrators clash with police during a protest in Westminster in central London December 9, 2010. Britain's parliament on Thursday approved plans to increase fees paid by university students despite a rebellion by members of the coalition government. Protesters had earlier clashed with police outside parliament in central London during the debate. [Photo/Agencies]

Demonstrators threw missiles and placards at police in the square in front of parliament. Mounted police then tried to break up the crowd in increasingly chaotic scenes.

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Police said they had attempted to contain protesters in the square after flares, snooker balls and paint balls were thrown at them. The protesters tried to push the police back using metal barriers.

Commentators said the vote was the biggest challenge faced by the coalition during its seven months in office.

"The vote on tuition fees will be the first ... acid test of how the coalition holds together," said Ben Page, chief executive of pollsters Ipsos MORI.

The honeymoon is over for the coalition parties, he said, but securing recovery from recession is voters' biggest worry.

"Tuition fees may be a storm in a teacup ... the state of the economy is absolutely the issue," Page said.

Inside parliament, the government defended the plans ahead of the vote on an issue which has divided the coalition and already sparked violent protests in London last month.

The bill is expected to pass in a vote on Thursday evening, but some members of the Liberal Democrats, the junior partner in the Conservative-led coalition, were expected to oppose it.

A handful of Conservatives may also rebel.

"Heavy handed"

Some protesters accused the police of being heavy handed.

"The police have been antagonistic in their approach to the demo. Everyone knows that if you compress a group of people they get nervous and a lot of people are frightened," said Elizia Volkmann, 39, an artist from London.

"There are many young people here under 17."

Police said they had made three arrests and that two officers had been injured, one of them with a serious neck injury after being knocked unconscious. A Reuters photographer was taken to hospital after he was hit in the face by a rock.

University students and school pupils have staged a series of protests in recent weeks, with hundreds of demonstrators arrested and a building housing the Conservative Party headquarters being attacked.

The government has made cutting a record peacetime budget deficit its priority and government departments have to reduce spending by some 19 percent over the next four years.

Business Secretary Vince Cable, who is a Liberal Democrat and responsible for higher education, told parliament the plan was progressive and would maintain high quality universities.

However, Greg Mulholland, a fellow Liberal Democrat, told parliament he would vote against it, saying it was not the fairest and most sustainable way of funding higher education.

The government plans to allow universities in England to charge students fees of up to 9,000 pounds ($14,100) per year -- almost treble the current limit, as it cuts state funding for higher education as part of an austerity programme.

The Liberal Democrats have angered their many young supporters and have been accused of betrayal for breaking a pre-election pledge to oppose an increase in fees.

Some commentators say the student protests could be a prelude to wider unrest as austerity measures start to bite and hundreds of thousands of jobs are lost in the public sector.

"I'm a public sector worker and I think it's about more than just tuition fees; it's about showing people are angry with the way the government are going about reducing the deficit," said Henry Trew, one of the protesters.