Cairo: Armed supporters of ousted Islamist president Mohammad Mursi briefly seized two soldiers in Cairo after dozens were killed in clashes outside an elite military headquarters on Monday, an army official said.

Both of the Egyptian soldiers, who were identified as Samir Abdullah Ali and Azzam Hazem Ali, “managed to escape their captors”, the official said.

The two had been put in a vehicle and forced to make pro-Mursi and anti-army statements on a loudspeaker, said the official, cited by state news agency Mena.

One soldier had been “severely beaten up” and filmed while making the pro-Mursi statements, he added.

The report came after an attack on Mursi supporters outside the Republican Guard headquarters in Cairo killed at least 42 people and injured hundreds, according to the emergency services.

The Muslim Brotherhood, which has led pro-Mursi demonstrations since the army ousted him on Wednesday, said 35 of its supporters were killed when police and troops fired at them while they were praying at dawn.

Witnesses, including Brotherhood supporters at the scene, said the army fired only tear gas and warning shots and that “thugs” in civilian clothes had carried out the deadly shooting.