An Egyptian military court has sentenced 11 Muslim Brotherhood members to life in prison for violence targeting the army in the port city of Suez last month.
Forty-five other Brotherhood members were handed five-year jail terms on Tuesday, and eight defendants were acquitted.
The men were accused of "shooting and adopting violent means" against the army in Suez on August 14 following a military crackdown in the streets of Cairo against supporters of the ousted President Mohamed Morsi.
Morsi belonged to the Brotherhood movement.
The Brotherhood was founded in 1928 and formally dissolved by Egypt's army rulers in 1954.
The Brotherhood operated for decades as a formally outlawed organisation until veteran autocrat Hosni Mubarak was deposed in 2011.
The movement then won a series of elections culminating in last year's presidential vote.
The military deposed Morsi on July 3 after mass protests against his rule.
Since then, most of the Brotherhood's top leadership has been arrested and face charges of inciting violence. Morsi was himself referred to trial on Sunday on that charge.
Meanwhile, Egyptian helicopters fired rockets at armed groups based in the northern Sinai peninsula, killing at least eight people.
At least a further 15 people were injured in the attack.
The security source said the two aircraft on Tuesday surprised gatherings of fighters in three houses in two locations, al-Muqataa and Touma, south of the town of Sheikh Zuweyid near the border with the Gaza Strip.
Attacks on security personnel have surged in Sinai after the toppling of Morsi on July 3.