Official Rangoon Radio said Friday prison guards opened fire on rioting inmates at three Burmese prisons, and witnesses said as many as 1,000 of the prisoners were killed at one of the jails.

Official Rangoon Radio Friday confirmed riots by prisoners at three prisons but indicated they were criminal offenders and had no connection with the more than two-week-old political unrest and street demonstrations sweeping Burma."About 2,000 prisoners in the No. 1 sleeping quarters in Insein Jail began rioting and setting fire to the jail's sleeping quarters" Friday morning, Rangoon Radio said.

It said "some prisoners and prison personnel" were wounded at the jail in Rangoon when "the prison security unit had to open fire" to prevent the inmates from forcing open the prison gates.

The official account gave no details or casualty figures.

But witnesses living near the prison, about 8 miles north of Rangoon's city center, said guards posted on the walls of the prison fired at thousands of prisoners attempting to break out. The witnesses said the inmates broke through some gates before they were cut down by gunfire from the guards.

They said the crossfire from the guards killed at least 500 and possibly as many as 1,000 of the prisoners, but the accounts could not immediately be confirmed.

A fire set by the inmates raged for several hours before being brought under control, said the witnesses, who asked not to be named.

Insein Prison is the central prison for Rangoon and usually holds about 10,000 prisoners.

On Thursday prisoners rioted inside Sittwe Jail in Rakhine state with the support of people outside the prison, the radio said. It said security police were forced to open fire, killing six prisoners and wounding 24.

"Despite attempts by the People's Police Force and prison personnel to control them, 1,600 prisoners managed to escape," the radio said.

The radio reported another prison riot erupted at Bassein Jail, 90 miles west of Rangoon on Wednesday when 200 people demonstrated outside the prison walls.

"The people bent on violence burned down the living quarters of the prison personnel, forcing the security unit to open fire," it said. "As a result, one person was killed."

It said 100 prisoners escaped during the violence there.

The radio said that the rioting prisoners at the three jails "were not detained in connection with the current unrest, but were imprisoned for committing criminal offenses."

The prison escapes reflected a general breakdown of law and order in Burma, where a mass protest movement in 21/2 weeks has forced two hardline presidents to resign and a third to propose steps to dismantle the one-party government.