NEW : Police pen hold demonstrators in for hours , a protester says . Students also protested in other cities across Britain , including Leeds , Cambridge and Birmingham . Students are angry about government plans to cut tuition increases . A large crowd filled the streets near Parliament in London . Other protests are reported in Leeds , Cambridge and Oxford .
NEW : Police pen hold demonstrators in for hours , a protester says . Students are angry about government plans to cut tuition increases . A large crowd filled the streets near Parliament in London . Other protests are reported in Leeds , Cambridge and Oxford .