Violent clashes between protesters and police outside the Houses of Parliament marred a protest by thousands of people against higher university tuition fees.

A car carrying Prince Charles and the Duchess of Cornwall came under attack after the couple found themselves among protesters on Regent Street, central London.

Their vehicle was kicked and splattered with paint. Despite a window being broken, the prince and duchess were unharmed. They had been making their way to the London Palladium for the Royal Variety Performance.

Police had been expecting about 20,000 demonstrators on the day of the Commons vote on plans to allow universities to increase tuition fees to up to £9,000 a year.

The National Union of Students had urged MPs to "do the honourable thing and vote down these damaging proposals". Despite some Lib Dem and Conservative MPs voting against the government, the plans were approved with a majority of 21.

However, an uneasy stand-off between police and protesters soon developed. During clashes, protesters hurled flares, sticks, snooker balls and paint at officers, while demonstrators complained at the police's policy of containing them in one area.

Some 43 protesters were taken to hospital. Officers started letting other demonstrators leave Parliament Square one by one later in the evening.

Scotland Yard said 12 officers were injured, with six requiring hospital treatment. The force confronted protesters in Parliament Square.

Demonstrators targeted the Treasury in the early evening, trying to gain access to the building by smashing windows.

Police said during the night there had been a total of 33 arrests. These included 12 for violent disorder and two for arson.