Riot police have clashed violently with students at the National University of Colombia in Bogota, Anastasia Moloney writes.
Demonstrators were showing solidarity with striking oil workers and were protesting against a scheme to privatise Colombia's largest state university and raise tuition fees.
What started as a peaceful gathering of some 100 students as part of the traditional May Day marches quickly escalated into a two-hour confrontation with police. Five students and a lecturer were injured.
A radical minority wanted to voice opposition to President Alvaro Uribe's aggressive handling of a strike at Colombia's national oil company. After the government declared the strike illegal, leading trade unionists were forced to resign. "We're showing solidarity with the oil workers," said German Romero, a law student at the university.
But others were demonstrating against reforms initiated by Marco Palacio, the controversial university rector who is believed by many to have been appointed by Mr Uribe for political motives.
Lorena Rodriguez, a history student, said that students were vehemently opposed to plans to privatise the university and to the increase in tuition fees. "I've seen a 40 per cent rise in my tuition fees in just two terms," she said.
Police are not allowed on campus without permission from the university's authorities. The vice-rector said that "the university did not call the police".
A university spokesman said: "The police made a mistake, striking at students and damaging university property in an indiscriminate manner."
Marcella Isaza, a sociology student, said: "From what I saw, no students who were demonstrating represented any threat to the safety of the students and staff."