CAIRO (Reuters) - Essam el-Erian, a senior leader of Egypt's Muslim Brotherhood, died in prison in Cairo on Thursday after suffering a heart attack, prison sources, a lawyer and local media said.
Erian, 66, had served as deputy leader of the Brotherhood's Freedom and Justice Party, and was swept up in a crackdown on the movement's leadership after it was forced from power in 2013.
He had been detained in Cairo's Tora prison along with other senior Brotherhood figures, and had been tried and sentenced in multiple cases linked to the turmoil that followed Egypt's 2011 uprising.
In June 2019 the Brotherhood's Mohamed Mursi, who was elected president in 2012 and deposed the following year in an ouster led by then-army chief and current President Abdel Fattah al-Sisi, died after collapsing during a court appearance at the Tora prison complex.
Erian had been moved to a prison hospital after suffering a heart attack and died during treatment, two prison sources said.
"We were informed of his death by prison authorities ... they told us the death was natural," said Abdel Moneim Abdel Maqsoud, a Brotherhood lawyer.
Egypt's public prosecutor had no immediate comment.
Relatives of other high-profile Islamist prisoners at Tora had previously raised concerns about their health, saying they were being held in poor conditions without adequate healthcare.
Rights group Amnesty International called on Egyptian authorities "to immediately order an investigation into the circumstances of his (Erian's) death, the conditions of his detention and the extent to which he received medical care".
Egyptian authorities have denied mistreating prisoners or neglecting their health.
Restrictions were placed on visits to Egyptian prisons in early March due to the novel coronavirus outbreak.
(Reporting by Ahmed Mohamed Hassan; Writing by Aidan Lewis; Editing by Giles Elgood and Daniel Wallis)