Backers of ousted Islamist president Mohamed Morsi are facing a deadly crackdown launched by the military-installed authorities since his ouster in July, with hundreds of people killed and thousands arrested.
A court in Egypt on Monday sentenced 529 supporters to death.
The sentence was delivered in the second hearing of a trial that began on Saturday in Minya, south of the capital.
Of those sentenced, 153 are in detention and the rest are on the run, the sources said, adding that 17 others were acquitted.
The verdict can be appealed.
Those sentenced are among the more than 1 200 Morsi supporters on trial in Minya.
A second group of about 700 defendants will be in the dock on Tuesday.
They are accused of attacking people and public property in southern Egypt in August, after security forces broke up two Cairo protest camps set up by Morsi supporters on August 14.
They are additionally charged with committing acts of violence that led to the deaths of two policemen in Minya, the judicial sources said.
The accused include several leaders of Morsi's Muslim Brotherhood, including its supreme guide Mohamed Badie.
The army ousted Morsi, Egypt's first elected and civilian president, on July 3 in a move that triggered widespread unrest across the deeply polarised nation.
Hundreds of people died in the August assault on the two Cairo protest camps and in subsequent clashes that day.
Rights group Amnesty International says at least 1 400 people have been killed in violence across Egypt since then, and thousands more have been arrested.
Morsi is on trial in three different cases, including one for inciting the killing of protesters outside a presidential palace while he was in office.
Morsi was removed after just 12 months as president following mass street protests against his rule amid allegations of power grabbing and worsening an already weak economy. – AFP