Some of the defendants, including award-winning photojournalist Mahmoud Abu Zeid, could face death penalty if convicted.

An Egyptian court has delayed a final ruling in a case against 739 people involved in a 2013 sit-in protest that was violently broken up by security forces, one of the bloodiest events in Egypt’s recent history.

The court said on Saturday the delay was due to “security concerns” which meant that defendants could not be transferred to the court.

The case, which involves top leaders of the banned Muslim Brotherhood, including the group’s leader Mohamed Badie, relates to a 2013 sit-in at Cairo’s Rabaa Square in support of President Mohamed Morsi after the army toppled him.

Some of the defendants, including an award-winning photojournalist, could face the death penalty if convicted on charges ranging from murder to incitement to violence.

International rights groups have condemned the trial.

“The idea that more than 700 people could all stand trial together in one day, all facing the death penalty in what is clearly a grossly unfair trial that violates Egypt’s own constitution beggars belief,” said Amnesty International’s North African campaigns director Najia Bounaim.

Almost 1,000 people were killed when security forces broke up the Rabaa protest and another one in Giza.

Foreign governments and rights groups have condemned the use of force to disperse the demonstrators.

Cairo has defended its actions, saying it had given protesters the opportunity to leave peacefully and that armed elements within the Brotherhood initiated the violence.

The Cairo Criminal Court had been expected to issue its final verdict in the case on Saturday, the anniversary of mass protests against Morsi’s rule in 2013 that prompted the army to move against him.

A judge said security concerns had stopped the defendants being transferred to the court and set a new hearing for July 28.

Two of Morsi’s sons were at the hearing, in which one of their brothers is a defendant, witnesses said.

Authorities outlawed the Brotherhood and designated it a “terrorist organisation” after Morsi was deposed.

They also dissolved its Freedom and Justice Party, and arrested thousands of its supporters before banning protests in a crackdown by President Abdel Fattah el-Sisi‘s government that rights groups say has muzzled freedom of expression.

Journalists caught in case

Photojournalist Mahmoud Abu Zeid, also known as Shawkan, who was arrested as he took pictures of the sit-in’s dispersal, is accused of belonging to a banned group and possessing firearms. He denies the charges.

International rights organisations, including Amnesty International and The Committee to Protect Journalists, have repeatedly denounced Shawkan’s imprisonment and urged Egyptian authorities to drop charges against him. Amnesty says he was imprisoned merely for doing his job as a photojournalist.

“We demand that all charges against him are dropped. We demand that the Egyptian government stops the suppression of human rights defenders who are being silenced simply because they criticise Egyptian authorities,” said Amnesty International’s Katia Roux.

The Egyptian embassy in Paris refused to accept a petition with more than 70,000 signatures in support of Shawkan.

He has been diagnosed with malnourishment, anaemia and depression, reported Al Jazeera’s Dayana Karim.

He has written a letter from his prison cell outlining the abuses he has faced and how journalism in Egypt has become a crime, according to Karim.