Egyptian authorities said on Friday they had arrested the acting leader of the Muslim Brotherhood, Mahmoud Ezzat, during a raid on an apartment in Cairo.
An interior ministry statement said Ezzat had been arrested from an apartment used as a hide-out in Cairo's Fifth Settlement district, and was accused of joining and leading a terrorist group and receiving illicit funds.
Ezzat was an influential former deputy to Brotherhood leader Mohamed Badie, and was seen as a hardliner within the group.
Ezzat became acting leader after Badie's arrest in August 2013.
The interior ministry said encrypted communications equipment had been seized during the arrest, and said Ezzat was suspected of overseeing several assassinations or attempted assassinations as well as a bombing since 2013.
Ezzat had previously been sentenced to death and to life in prison in absentia. According to Egyptian law, he will face retrials in the cases following his arrest.
Badie remains in prison in Cairo, where he has received several life sentences.