Cairo criminal court sentenced on Tuesday 8 defendants to life in prison over charges of joining an lawful group and communicating with a terrorist organisation, in the case publicly known as "Daesh (IS group) in Cairo."
Three of the defendants were tried and convicted in absentia.
The charges also included attacks on public and private property.
A life sentence amounts to 25-years in jail, according to Egypt’s penal code.
In November 2014, Egypt banned and designated the IS group as a terrorist group.
Egypt's army and police have been battling an Islamist insurgency in parts of North Sinai by the IS-affiliated Ansar Beit Al-Maqdis since 2013.
Deadly militants attacks against security forces have left hundreds of security personnel killed.
The army says it also killed hundreds of militants.
Islamist militants have also carried out several attacks on public institutions and assasinations of public figures in Cairo and other cities.
In mid-October, President Abdel-Fattah El-Sisi extended a state of emergency in designated areas of the North Sinai governorate, which was originally declared in certain areas of the restive province in August 2013, for three months.