Updated

Egypt's highest appeals court has upheld death sentences for four people over forming a "terrorist cell" to plot attacks on security forces and other institutions.

The court of cassation on Sunday also rejected an appeal by 14 other defendants against sentences of 15 years imprisonment in February over similar charges including joining an outlawed group, a reference to the Muslim Brotherhood. The verdict is final.

Six defendants in the case were sentenced to life imprisonment in absentia. They remain at large and will be re-tried once they are apprehended.

Egypt has cracked down on suspected Islamists since the military ousted president Mohamed Morsi of the Brotherhood in 2013.

Since then, hundreds of Islamists, including Brotherhood members, have been sentenced to death. The authorities have carried out dozens of executions.