Cairo: An unprecedented ruling by an Egyptian court, sentencing 529 Islamists to death, has raised concerns among rights advocates and drawn condemnation from the now-outlawed Muslim Brotherhood.

“This shocking verdict raises several questions,” said Hussam Rahmi, a rights activist. “It was issued in the second session of the trial. Had the court heard defence lawyers’ arguments and examined the evidence related to the case? Even the two hearings were closed to the media,” Rahmi added.

“I think this ruling, although it can be appealed, will further increase the political tensions in the country and will win the Brotherhood sympathy.”

The Criminal Court in Minya, around 250km south of Cairo, Monday handed down the death sentence to 529 backers of the ousted Islamist president Mohammad Mursi of the Brotherhood and acquitted 16 others in the same case.

The convicts were charged with illegally possessing weapons, attacking state-owned institutions including a police station, killing a senior security official in Minya in the violence that broke out in the city in August last year following security forces’ evacuation of two pro-Mursi protest camps in Cairo. Hundreds were killed in the Cairo crackdown.

The court said in the ruling announcement that the death sentences will have to be ratified by Egypt’s top Muslim cleric, the Mufti, before the final ruling is declared on April 28. Rarely does the Mufti disapprove the death sentences.

Following the ruling announcement, security was tightened across Minya for fear of a backlash, according to state television. Angry families of the convicts torched a school in the city, media reports said.

The Brotherhood has slammed the ruling as an “unfair precedent”. “This is a new crime committed by the military coup. It exposes the collusion of traitors and agents inside state institutions against the free patriots, who will not be intimidated by such an unfair ruling,” the Brotherhood said on its website.

“This ruling is void because the trial procedures were marred by invalidity,” said Mohammad Toson, a Brotherhood-affiliated lawyer. “The presiding judge did not make sure that all the defendants had appeared. Nor did he heed the defence lawyers’ requests.”

Around 145 of the defendants have been in police custody, while the remainder are at large, according to judicial sources.

“Many of the accused were randomly rounded up and have nothing to do with the case,” said Toson, who said defence lawyers will appeal against the ruling.

The same court is due Tuesday to start the trial of more than 600 Islamists, including the Brotherhood’s head Mohammad Badie, on charges of instigating riots and vandalising public installations.

Thousands of the Brotherhood’s leaders and followers have been detained allegedly for inciting or involvement in violence since the military deposed Mursi in July last year. The Islamist group has frequently denounced such charges as politically motivated.

The military-backed government has repeatedly said courts are independent.

“Claims that the judiciary is biased against the Brotherhood are baseless,” said Shukri Abdul Moneim, a legal expert.

“One clear evidence is that the Brotherhood defendants are being tried before ordinary courts and are given the right to defend themselves despite their repeated attempts to disrupt hearings,” he added. “The Minya court issued the sentences based on the evidence available to it. The ruling is not irreversible and can be appealed.”