Egyptian authorities have detained senior Muslim Brotherhood leader Essam el-Erian, the latest arrest in a government crackdown against the Islamist movement, Reuters reported, citing an Interior Ministry source.
Erian, the deputy leader of the Brotherhood's Freedom and Justice party, was taken into custody from a residence in Cairo where he had been in hiding.
"Yes, he's been arrested and details will soon be released," the source told Reuters.
A court in Cairo has banned all activities of the Muslim Brotherhood in Egypt.
There were fears the verdict could trigger more violent protests.
Egyptian police have captured senior Muslim Brotherhood official Mohamed El-Beltagi ,security sources told Reuters.
Beltagi appeared in a recorded statement aired by the Qatari-owned Al Jazeera television news network this week in which he urged Egyptians to join rallies against the military on Friday.
The crackdown on the group began after Egypt's army deposed President Mohamed Mursi, a Muslim Brotherhood member, on July 3rd.
Egyptian security forces have arrested the spiritual leader of the Muslim Brotherhood, state media reported.
Mohamed Badie was detained at a residential flat in Nasr City in northeast Cairo, the state news agency reported.
Egypt's ambassador to London has shown reporters a series of videos which purport to show gunmen firing at security forces from the midst of Muslim Brotherhood demonstrators.
Ambassador Ashraf Elkholy said the videos show gunmen shooting from the midst of unarmed protesters before taking cover, and even shooting people on their own side of the barricades by accident.
ITV News cannot independently confirm the veracity of this video.
The Egyptian presidency has said that diplomatic efforts to end the political crisis in the country have failed, state media reports.
The statement blamed the Muslim Brotherhood, whose member Mohamed Morsi was deposed, for the break down in talks.
Muslim Brotherhood supporters are gathering in large numbers in Cairo ahead of Friday prayers and protests.
Rival demonstrations supporting the overthrow of Mohamed Morsi are also planned.
Everyone is wondering whether this will be another day that ends in violence.
The Egyptian prosecutor's office has ordered the arrest of Muslim Brotherhood leader Mohamed Badie on charges of inciting violence, state news agency MENA reported.
The office also ordered the arrest of other senior Brotherhood officials, including Badie's deputy Mahmoud Ezzat and party leaders Essam el-Erian and Mohamed el-Beltagi, it stated.
The charges relate to what Egypt's military described as an "assault" by supporters of ousted president Mohamed Morsi on the Republican Guard headquarters on Monday, which left 55 people dead.
The Muslim Brotherhood said its leaders have yet to be detained.
Spokesman Gehad el-Haddad said the charges were "nothing more than an attempt by the police state to dismantle the Rabaa protest," a vigil being held by its supporters at the Rabaa Adaweya square in northeastern Cairo.