A leader of the hardline Islamist group Al-Gamaa Al-Islamiya has died in jail after being detained for almost three months, the group said on Sunday.
Essam Derbala, 58, spent over two decades in prison under former president Hosni Mubarak during the group's armed insurgency against the state in the 1990s.
The group said on its website that Derbala was "denied medicine, which caused him to fall into a deep coma that resulted in his death."
The group blamed authorities for his death, describing it as "murder."
The interior ministry said in a statement that Derbala suffered fatigue on Saturday and died while being transferred to the hospital due to "a haemorrhage from the nose and a drop in blood pressure and respiration."
He was arrested in mid-May of this year on charges of belonging to an outlawed grouping supporting the blacklisted Muslim Brotherhood.
Interior minister aide Hassan Abdel Razak, Who is in charge of security in Minya, said necessary security measures have been taken to counter violence before, during or after the burial of Derbala, Al-Ahram's Arabic site reported.
Al-Gamaa Al-Islamiya was behind the massacre of 62 people, 58 of whom were foreign tourists, at a Luxor temple in 1997. The attack was part of a broader Islamist insurrection at the time that Mubarak struggled to crush.
The movement was also implicated in the 1981 assassination of Mubarak's predecessor Anwar Sadat, but formally renounced violence a decade ago.
Many of the movement's members, jailed for decades under President Mubarak, were freed shortly after his ouster in 2011, with many becoming active on the political scene.
The Egyptian government designated the Muslim Brotherhood a terrorist organisation following Morsi's ouster in 2013, and banned a campaign group that had pushed for his reinstatement almost a year later.