Khartoum - Sudanese police fired tear gas Thursday as clashes broke out during a protest at Khartoum University over the killing of a student by security forces, an AFP correspondent reported.About 1 000 students staged a fresh demonstration at the campus on the banks of the Blue Nile in central Khartoum, the scene of regular protests.Demonstrators were protesting the killing of a student on Wednesday when angry students clashed with security forces at a university in the capital's twin city of Omdurman.The student was shot dead during clashes outside the campus, President Omar al-Bashir's National Congress Party said.On Thursday, heavy clashes erupted between students and riot police in front of Khartoum University, the AFP reporter said."Killing of student means revolution! Killing of student means killing nation!" chanted hundreds of students as they clashed with riot police, who chased protesters down nearby streets.Similar protests were also staged by students in a university in Port Sudan, east of the capital.Sudanese students have held several protests over the past few days in Khartoum and Ahliya University in Omdurman, where the student was killed.Police also used tear gas on Tuesday when students demonstrated in Khartoum University against what they said was a plan to sell off buildings belonging to the institution. The government has denied the charge.