CAIRO — Clashes erupted between supporters and opponents of Egypt’s ousted president during nationwide protests Friday as the military battled Al Qaeda-inspired groups in northern Sinai.
The street rallies came a day after Egypt’s military-backed interim government extended a nationwide state of emergency by two months, citing ongoing security concerns.
Officials said they feared more terrorist attacks after a failed assassination attempt targeting Egypt’s interior minister last week and suicide attacks this week at a military intelligence headquarters and a checkpoint in Sinai that killed six people.
Unrest in Egypt spiked after the popularly backed July 3 military coup that toppled President Mohammed Morsi. The interim government has responded by targeting members of Morsi’s Muslim Brotherhood for arrest and detention.
Many Brotherhood members, like Essam el-Erian, who is wanted on charges of inciting violence and murder, remain on the run.
‘‘We will not give up our rights,’’ said Erian, urging more protests in a video aired on Al Jazeera Mubashir Misr, a network affiliate. ‘‘We will not surrender to an oppressive power that only speaks the language of the bullets.’’
The security crackdown has affected the group’s ability to mobilize in the streets to protest Morsi’s ouster. But on Friday, demonstrations appeared to be larger than usual, and several descended into violence.
In the coastal city of Alexandria, hundreds of Brotherhood supporters marched after Friday prayers from a main mosque to a major thoroughfare, where they confronted a rally by Morsi opponents.
State television showed footage of anti-Morsi protesters tearing down Morsi posters and chasing Brotherhood supporters through the streets.
Authorities said the two sides hurled stones at each other as gunshots rang out. Security forces broke up the melee by firing tear gas and arresting a number of protesters. One person was killed and five injured in the clashes, Egypt’s state news agency MENA reported.
In the industrial city of Mahallah, riot police fired tear gas to disperse another Islamist demonstration near a police station, officials said.
Several television crews also came under attack by Morsi supporters, and Al Hayat TV and state-run networks said protesters stole their live transmission equipment.
The Brotherhood-led coalition earlier announced a blacklist of journalists it accused of inciting public anger against the group.
Across Egypt, crowds of Morsi supporters raised yellow placards showing an open palm with four raised fingers, the symbol that has come to represent the site of the main pro-Morsi encampment raided by security forces on Aug. 14, sparking violence that left hundreds dead and thousands wounded. Some demonstrators carried pictures of the slain protesters while chanting, ‘‘It is a military coup.’’
‘‘After all the massacres and after seeing people die in front of my eyes, you have to take to the streets,’’ said Haitham Mohammed, 28, who said he lost three friends in the dismantling of the protest camp.
Some Cairo residents blamed the demonstrators for Egypt’s economic downturn and the security woes plaguing the country.
‘‘The state should respond strongly against those protests because they are slowing down the economy,’’ said Ali Abdel-Karim. ‘‘If I were a state official, I would just kill them all.’’
In Sinai, helicopter gunships targeted suspected Islamist militant hideouts in villages south of the town of Sheikh Zuweyid and farmlands near the city of el-Arish at sunrise, said a military official, who spoke on condition of anonymity because he was not authorized to speak to journalists.
Sheik Hassan Khalaf, who lives in a village three miles from the targeted areas, said he saw smoke billowing after hearing explosions starting at 5 a.m.
‘‘I think the suicide attacks are a desperate attempt to repel a military assault,’’ Khalaf said by telephone. ‘‘As a resident here, I hope the military never stops until they are all out of here.’’
Friday’s attack was part of an offensive launched last week by the Egyptian military in Sinai, following militant attacks that have killed more than 70 police officers and soldiers.