The Muslim Brotherhood said on Monday that the death of former Egyptian President Mohammed Morsi, a member of the group, was a “full-fledged murder” and called on Egyptians to gather for a mass funeral, Reuters reported.
In a statement on its website, the Brotherhood also called for crowds to gather outside Egyptian embassies around the world.
Meanwhile, Amnesty International urged Egyptian authorities to investigate Morsi’s death.
"We call on Egyptian authorities to conduct an impartial, thorough and transparent investigation into the circumstances of Morsi's death, including his solitary confinement and isolation from the outside world," Amnesty tweeted in Arabic, according to Reuters.
It also called for an investigation into the medical care the former president was receiving, and for anyone found responsible for mistreatment to be held accountable.
Morsi, the first democratically elected head of state in Egypt’s modern history, died at the age of 67 after collapsing in a Cairo court while on trial on espionage charges.
He was ousted by the army in 2013 amid mass protests against his rule.
In 2016, Egypt's highest court overturned the death penalty to which Morsi and five other leaders of the Muslim Brotherhood were sentenced for their roles in organizing the mass prison break at the Wadi Natroun prison in 2011.
Prosecutors said Morsi and his supporters were assisted by Hamas and Hezbollah in organizing the prison break.
Morsi had already been sentenced to a total of 45 years in prison in various trials. In December of 2017, he was sentenced to three years in prison for "insulting the judiciary".
In September of that year, a court in Egypt upheld a life sentence against Morsi on charges stemming from a trial over spying for Qatar.
In 2015, he was sentenced to 20 years in prison after being convicted of inciting the killing of protesters, in an incident that saw 10 people gunned down outside the presidential palace in December 2012.