Iranian riot police today forcibly broke up a procession of several thousand dissident marchers in the second day of violent university incidents linked to demonstrations in Washington against the visit of Shah Mohammed Reza Pahlevi.

Eyewitnesses said scores of dissidents, mostly students, were injured when helmeted riot police wielding wooden truncheons charged without warning from an intersecting street and began clubbing the marchers.

It was the most violent police-student clash in recent years and appeared aimed at stemming the rising tide of dissident activity in Iran the past few months.

Two Western reporters who were manhandled in the melee said the demonstrators were walking peacefully when about 500 police charged. The government had no immediate comment on the confrontation.

The incident followed a clash last night in which a crowd of some 2,000 dissidents at Aryamehr University began shouting anti-shah slogans in a demonstration supporting protests in Washington.

Riot police moved in on the crowd and witnesses said 30 to 40 of the protestors were injured and about 50 were arrested. The demonstrators then went on a rampage, smashing the windows of at least six banks and two car showrooms.

Last night's clash grew out of poetry reading at Aryamehr University on Tehran's west side in which Sayid Soltanpour, a leftist writer who was released from prison here earlier this year, was to have read his works. About 4,000 people were admitted to gathering, which was organized by the Writers Assocation of Iran, one of several newly emerged dissident groups.

Police then shut the university gates, leaving about 2,000 people outside. Of the 50 persons reportedly arrested later, 16 were released, student leaders said. The 4,000 people in the university then refused to leave until the rest had been freed and staged a sit-in through the night at the school's gymnasium, where the poetry reading was scheduled.

Today demonstrators marched from the university toward central Tehran to protest the police action and were joined by students from Tehran University, which students boycotted in sympathy. The demonstrators - some estimates put the number as high as 10,000 - were stretched in long line down the sidewalk when the police charged.

"The police were in a very ugly mood," one Western eyewitness said. He said he saw beatings, including one in which four or five policemen clubbed a girl.