Police carried away at least five people, apparently all dissidents, during the incident in front of the Capitolio, Cuba's former capital building.
The 20-minute disturbance was one of the most public outbursts in Havana since a clash between thousands of Communist Party militants and protesters near Havana's Malecon waterfront in 1994.
About a dozen dissidents had arrived to support Mario Viera, the 59-year-old head of the tiny and unauthorized Cuba Verdad press agency. He was to go on trial Friday on charges of defaming a government official in an article posted on Cubanet, a Miami-based Internet page that mixes dissident and official news from Cuba.
Apparently attracted by the television cameras focused on Viera, supporters behind him began loudly chanting the prayer ``Our Father Who Art in Heaven.'' One shouted ``Long Live Mario, who defends the liberty of Cubans!''
That rapidly attracted government supporters, some shaking with apparent rage. ``I am a Cuban! I am a revolutionary!'' Marta Ofelia Cuallo Portuondo shouted at the dissidents and television crews.
Other people walked up -- one carrying a Cuban flag -- and began shouting at the dissidents. ``Viva Fidel!'' cried one man.
One man lurched out and slapped at Norberto Miranda of the small education organization College of Pedagogues, then chased Miranda down the street.
Police and dozens of onlookers followed and journalists saw police take away Miranda, one of them kicking him.
Taken away in police cars were Dr. Oscar Elias Vicel, president of the Lawton Foundation, an apparent dissident group, and a woman carrying a cane for the blind, identified by dissidents as Milagros Cruz.
A few minutes later, two other women were taken away by police. Through the windows of the police car, they held up and grabbed their wrists to simulate handcuffs. Their identities were not immediately known.
Viera was scheduled to go on trial at the Havana provincial court, on a side street near the Capitolio, on charges of ``injury'' for allegedly defaming Foreign Ministry official Jose Dionisio Peraza.
Peraza filed a complaint charging that Viera had defamed him with an article, ``Morality in Underwear,'' ridiculing his statements before a conference in Rome on a proposed international criminal court.
Viera said outside the courthouse Friday that Peraza insisted the court be independent, but that Cuban courts themselves ``are neither independent nor impartial.'' Cuban officials insist that their courts are both.
The Cuban Foreign Ministry on Thursday distanced itself from the case, saying it was a private affair between Peraza and Viera.
Viera's attorney, Jose Angel Izquierdo, said it was not clear if the trial would go forward or be suspended.
If convicted, Viera said he could receive one year in prison, with an additional six months if he refuses to retract his statement.
Viera said he lost his job as an agronomist in 1988 because of his political beliefs, and was twice imprisoned on charges of trying to leave the country illegally without a required permit, for one year in 1991 and for two in 1994.
© Copyright 1998 The Associated Press