At least two people have been killed in the latest anti-governement protests in Egypt.
Violence erupted in the province of Fayoum, south of the capital Cairo, after supporters of ousted President Mohamed Morsi staged rallies following Friday prayers. A teenage boy was killed, medical and security sources said.
There were conflicting reports of whether he was killed in clashes with police or between residents and protesters. Health Ministry official Medhat Shukri said three policemen were also wounded in the violence.
Another person was killed when protesters clashed with government supporters in the Ain Shams district, northeast of the capital, a Cairo police official said.
Security officials said that 13 protesters were arrested, including five in Fayoum, who were found in possession of petrol bombs.
Protests against the government have been held since the army overthrew Morsi last July following mass protests against his rule .
Demonstrations have been staged in his support. However they lost strength after a fierce security crackdown against his Muslim Brotherhood party.
At least 1,400 people have been killed, while more than 15,000 others have been jailed and hundreds sentenced to death.
'War without end'
Meanwhile, the government says anti-state violence has killed more than 500 people, mostly police and soldiers in the last year.
On Friday, security sources said one civilian was killed and one wounded when gunmen opened fire on an army checkpoint near the Suez Canal city of Ismailia.
The latest attack on the army came hours before a self-declared jihadist group operating in the country threatened to escalate its assaults on military targets.
The Sinai-based Ansar Beit al-Maqdis [Partisans of Jerusalem], the most active armed group in Egypt, said it was engaged in a "war without end".
"We will continue to fight the army until the day of judgement," said a recording posted on Twitter by the group that has pledged allegiance to al-Qaeda.
The latest threat comes two weeks after a suicide bomber in a vehicle blasted a security checkpoint in the north of the Sinai Peninsula, killing 30 soldiers.
However, no group has yet admitted responsibility for the deadliest attack on the military since Morsi's overthrow.