Security forces have been deployed in the vicinity of Cairo's police academy on Sunday morning ahead of the espionage trial of deposed president Mohamed Morsi.
Dozens of police vehicles and checkpoints are guarding the court venue, Al-Ahram Arabic news website reported, while the defendants have already arrived by helicopter.
Morsi and 35 Muslim Brotherhood members are accused of collaborating with foreign organisations to commit acts of terrorism in Egypt, revealing defence secrets to a foreign country, funding terrorists and organising military training "to achieve the purposes of the international organisation of the Brotherhood," according to a prosecution statement.
The prosecution specifically accuses the Brotherhood members of collaborating with Gaza rulers Hamas, Lebanese Shia group Hezbollah and other organisations "inside and outside" Egypt to smuggle arms, organise military training for group members in the Gaza Strip, and funding a scheme to stir chaos and threaten national security in Egypt.
Hamas has frequently denied being linked to any unrest in Egypt.
They are also accused of sponsoring terrorist attacks against army and police targets in the Sinai Peninsula - which borders Israel and Gaza - following Morsi's ouster.
Morsi's presidential aides, including his national security advisor Essam El-Haddad, are accused of divulging secret reports to the international organisation of the Muslim Brotherhood, the Iranian Revolutionary Guards and Hezbollah in return for their cooperation in terrorist operations.
The charges against the defendants span the period between 2005 and 2013.
The accused include Brotherhood Supreme Guide Mohamed Badie, former speaker of parliament Mohamed El-Katatni, and Ahmed Abdel-Ati, ex-head of Morsi's presidential office.
Nineteen of the defendants, including Morsi, are already behind bars. The public prosecutor has issued an arrest warrant for the remaining 17.
Morsi, Egypt's first freely elected president and a Brotherhood leader, was ousted on 3 July by the military amid mass protests against his troubled one-year rule.
He is also standing trial for incitement to murder and violence during clashes between his supporters and opponents at the Ittihadiya presidential palace on 4 December 2012. The clashes resulted in the death of eight people, including at least four Brotherhood members.
Morsi is also on trial along with 130 co-defendants in the 'jail break' case.