An Egyptian court handed death sentences to more than 500 supporters of the country's ousted president on Monday, lawyers said.
The 529 members of the Muslim Brotherhood were accused of a deadly attack targeting police in Cairo last August.
The court in Minya, north of Cairo, issued its ruling after just two sessions in which the defendants' lawyers complained they had had no chance to present their case, The Associated Press reported.
The ruling was described by Cairo-based rights lawyer Mohammed Zarie as "way over the top and unacceptable."
"It turns the judiciary in Egypt from a tool for achieving justice to an instrument for taking revenge," Zarie told the AP.
The Muslim Brotherhood was classified as a terrorist organization by Egypt's military government after its former leader, President Mohammed Morsi, was deposed and arrested last year.
The charges relate to violence in Cairo in August, which resulted in one police officer being killed. The riot was a backlash against a police crackdown on two pro-Morsi sit-in protests on Aug. 14.
In addition to the 529 sentenced to death, 16 were acquitted, lawyer Ahmed al-Sharif told Reuters after the ruling, which can be appealed.
Only 123 of the defendants were present at the hearing, the rest were either released, out on bail or on the run.
Hundreds of Muslim Brotherhood members have been killed in clashes with police and thousands more arrested since Morsi was overthrown.
Monday's ruling came the same day as a group of Al Jazeera journalists were due to begin their trial in Cairo on being associated with the Brotherhood.
The Associated Press and Reuters contributed to this report.