PORT-AU-PRINCE, Haiti - Police blocked students from joining a protest Thursday demanding President Jean-Bertrand Aristide's resignation, while his supporters demonstrated freely just blocks away.

Riot police cut off the protest route with trucks and stood in the way of some 200 protesters, who milled about outside the State University medical school chanting "Aristide must go!"

Police fired tear gas to keep back about 100 Aristide supporters, some of whom threw rocks and bottles at officers. No one was reported injured, and student protesters dispersed peacefully after a few hours.

About 1,500 students who support Aristide marched a few blocks away, calling for new legislative elections, which the opposition has refused unless Aristide resigns.

It was the third time in a week that police have blocked a student demonstration. On Monday and Wednesday, police fired tear gas and warning shots near the university to keep back students.

Haiti has been in turmoil since Aristide's party swept 2000 legislative elections that observers said were flawed. In the past four months, at least 47 people have been killed during protests calling for Aristide to resign.

Aristide has said he will not step down before his term ends in 2006.