Thousands of university students demonstrated Thursday in central London, the fourth since last month, as MPs in the House of Commons prepared to vote on a plan to raise tuition fees.

An injured protester is taken care of by his friends in London, Britain, Dec. 9, 2010. Over 20,000 students took to streets to protest against the coalition government's plan to raise the tuition fees cap in England from 3290 to 9,000 pounds per year, which was passed in the House of Commons Thursday. More than a dozen of policemen and students have been injured during the clash. [Zeng Yi/Xinhua]

Students from around the country took part in the latest protest, during which barricades were set up around the Houses of Parliament.

Ahead of the vote, Prime Minister David Cameron insisted that raising tuition fees would widen access to universities, creating incentives to improve the quality of courses.

But the University and College Union's Sally Hunt criticized the plan, warning "it will be an issue for tens of thousands of students and their hardworking families."

The British government confirmed that university undergraduate students will be charged tuition fees of up to 9,000 pounds (14,300 U.S.dollars) a year from 2012 from the current 3,290 pounds (5,200 dollars).

Under the plan, graduates earning more than 21,000 pounds(33,200 dollars) per year will start repaying their loans at 9 percent of their income at a real rate of interest, up from the current threshold of 15,000 pounds (23,700 dollars), with outstanding loans written off after 30 years.

The British university students have staged three waves of demonstrations against the planned tuition fee rise in London and other cities since last month, resulting in confrontations with police and arrests.