Reuters reports that an Egyptian court sentenced 75 people to death on Saturday including prominent opposition leaders Essam al-Erian and Mohamed Beltagi over a 2013 sit-in which ended with security forces killing hundreds of protesters.
The sentencing, which included jail terms for more than 600 others, concluded a mass trial of people accused of murder and inciting violence during the pro-Muslim Brotherhood protest at Rabaa Adawiya square in Cairo.
The decision can be appealed within 60 days.
Rabaa square was the single most deadly incident in unrest which followed the 2011 popular uprising that toppled Egypt's longtime leader Hosni Mubarak.
It occurred weeks after the military ousted Egypt's first freely elected head of state, president Mohamed Morsi.
The government says many protesters were armed and that eight members of the security forces were killed.
Rights groups say more than 800 protesters died. Amnesty International condemned Saturday's decision, calling the trial "disgraceful".
Those sentenced to jail included a US citizen, Moustafa Kassem, rights group Pretrial Rights International said. Washington is Cairo's closest Western ally and one of its top aid donors.
President Abdel Fattah al-Sisi on Saturday met US Central Command chief General Joseph Votel as the two countries launched a joint military exercise off Egypt's Mediterranean coast.
In Saturday's hearing at the vast Tora prison complex south of Cairo, a criminal court sentenced to death by hanging several prominent opposition leaders including senior Brotherhood leaders al-Erian and Beltagi and preacher Safwat Higazi.
Muslim Brotherhood spiritual leader Mohamed Badie and dozens more were given life sentences, judicial sources said. Others received jail sentences ranging from five to 15 years.
Cases were dropped against five people who died while in prison, judicial sources said.
Following weeks of protests against the ouster of President Morsi by the military, which at the time was led by current president Sisi, security forces violently broke up the Rabaa square demonstration.
They arrested hundreds of people who were charged with inciting violence, murder and organising illegal protests.