Armed supporters of deposed president Mohamed Morsi briefly seized two soldiers in Cairo after dozens were killed in clashes outside military headquarters, an army official said.

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

The two were put in a vehicle and forced to make pro-Morsi 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-Morsi statements, he added.

The abductions came after an attack on Morsi 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-Morsi demonstrations since the army ousted him on Wednesday, described the killings as a "massacre" and called for an "uprising" in the country.

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.

Source: AFP