Hundreds of student protesters have clashed with police during a rally against higher tuition fees in London. They broke into Conservative HQ, smashing windows and wrecking a lobby.

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Crowds of student protesters broke into 30 Millbank, where the Conservative Party's headquarters are based, smashing the windows and wrecking the lobby as the peaceful demo turned ugly.

They got onto the roof, lit fires and threw missiles at police - who have admitted to Channel 4 News that they were "embarrassed" at being outnumbered.

Dozens have been arrrested and ten people needed hospital treatment after the violent clashes during which demonstrators chanted "Tory scum" at plans to increase the cap on university tuition fees.

Student leaders are furious their protest was hijacked - but hundreds if not thousands of marchers abandoned the official route of the protest and effectively joined the siege.

Met Police Commissioner Sir Paul Stephenson said: "It's not acceptable. It's an embarrassment for London and for us."

He added: "I am determined to have a thorough investigation into this matter. We didn't expect this level of violence."

FactCheck - Student fees: will higher earners pay back 'over the odds'?

Student protests: a demonstrator hurls a chair at Millbank Towers. (Getty)

Hundreds of people were evacuated when trouble flared at Millbank in the heart of Westminster.

One eyewitness who works in the targeted building, but did not want to be named, said: "The fire alarm went off and every one was evacuated from the building. There are hundreds of students outside.

"We were told that it was a false fire alarm because students were throwing smoke bombs into the building."

Thames House, the MI5 headquarters close by, was sealed with heavy metal doors and police were deployed to guard the rear exits.

This is only the beginning of the resistance to the destruction of our education system and public services. Protesters' statement

Dozens of demostrators climbed onto the roof of the building next to 30 Millbank. One worker said individual floors were taking the decision to send staff home early.

The protesters inside and on the roof released a statement which said: "We oppose all cuts and we stand in solidarity with public sector workers, and all poor, disabled, elderly and working people.

"We call for direct action to oppose these cuts. This is only the beginning of the resistance to the destruction of our education system and public services."

Chief Correspondent Alex Thomson blogs from the wrecked lobby at 30 Millbank:
Two quite different actions taking place now.

Inside the smashed up reception area of 30 Millbank, police transits come and go, transporting away protesters arrested inside Tory Party HQ.

They edge gingerly out in the arms of riot police past the smashed doors and wrecked windows across the courtyard filled with leaflets, smashed placards, cans and the ash of small fires.

Thirty yards away on London's embankment, still closed to traffic, perhaps a couple of hundred demonstrators remain corralled.

But there is movement. One by one they are led out to an area where several groups of police officers are videoing them, asking questions, and noting down details.

Thus the kettle is being emptied at an immensely slow pace. This process is likely to take several hours but the police have not told us under what powers they are able to do this. I have seen the same operation at G20 and a number of other protests.

What is clear is that - as one might expect - these students did their homework, clearly outflanking the police in reaching Millbank in numbers before they did. I can see both sides making something of this - the Police Federation may well use it as ammunition for their argument for funding, just like the students.

One curious fact though today, I spoke to three different policemen in very different areas, all of whom said there would be a lot more of this and expressed considerable sympathy with what happened here today.

That sentiment echoed too by a 54-year-old office manager of a charity, who looked at the damage here and said that phrase we have heard so much today: "this is only the beginning".

These students of cojurse will not remember, and nor can I, the events of May '68 in Paris and the student slogan then: "C'est n'est tu'un debut" - this is only a start.

They will not even remember perhaps the poll tax riots in Trafalgar Square where there was a genuine riot and widespread damage.

The point being that violent demonstration sometimes works. A short time after that event the hated poll tax and indeed Margaret Thatcher were history.

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Largest student demo in a generation

The rally and march, in the centre of London, followed Lord Browne's review which recommended the Government raise tuition fees to help fund higher education. It is estimated around 30,000 students and lecturers took part.

As Nick Clegg stood in for David Cameron at Prime Minister's Questions, students warned they will attempt to oust Liberal Democrat MPs who vote for a tuition fee hike.

We should be clear that the Government has asked students to pay three times as much for a quality that is likely to be no better than what they are receiving now and perhaps worse. Aaron Porter, NUS President

Aaron Porter, president of the National Union of Students (NUS), said they will try to force a by-election in the constituencies of MPs who renege on a pre-election pledge to oppose any hike.

He said that swingeing cuts to university teaching budgets laid the groundwork to justify trebling fees.

But Mr Porter added: "We should be clear that the Government has asked students to pay three times as much for a quality that is likely to be no better than what they are receiving now and perhaps worse."

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Universities Minister David Willetts told Channel 4 News the following measures are being taken to help students:
The system we will introduce takes people's different circumstances into account.

No eligible student will be expected to pay tuition charges upfront. They will be able to apply for loans - including, at last, part-time students.

We will introduce a £150 million national scholarships programme. This will include different kinds of support, including a free first year for students from the most disadvantaged backgrounds, and a foundation year for young people with high potential but lacking qualifications.

We will also introduce a more generous student support package that's linked to family income.

Graduates will not need to repay their loans until they earn £21,000 (increased from the current £15,000). If your salary falls beneath £21,000, repayments will stop.

For graduates earning under £21,000, the real interest rate will be zero - as now.

Graduates who earn more will repay their loans at a higher rate of interest.

If, after 30 years, a graduate has not paid off all of his or her loans, the remainder will be written off.