Riot police swung batons and fired volleys of tear gas to separate stone-throwing Brotherhood members and ultraconservative Salafis on one side, and youthful secular protesters on the other.
The clashes started when the two groups met just after Friday prayers at the city’s main Qaed Ibrahim mosque, by the coastal promenade. Throngs of Salafi Islamists, most wearing the long beards favored by the movement, had gathered there for what they called ‘‘a rally to defend clerics and mosques.’’ Waving black Islamic banners, some chanted ‘‘God is Great!’’ and warned opponents: ‘‘With blood and soul, we redeem Islam.’’
It was unclear who started the fight. During the battles, secular youths set fire to two buses and two cars belonging to Islamists, sending thick black smoke through the upscale city center. Under a heavy cloud of tear gas, the two sides pulled back, but then continued fighting for hours past dusk along the corniche, near the famed Alexandria Library.
At least 42 people were treated for injuries, with some rushed to the hospital, a city health official said.
The Islamists’ rally was called in response to violence last week, when a well-known Salafi cleric in Alexandria, Sheik Ahmed el-Mahalawi, was trapped inside a mosque for 12 hours while his supporters battled stone-throwing opponents outside with swords and firebombs.
El-Mahalawi, 87, had stirred anger with a sermon in which he denounced opponents of the draft charter as ‘‘followers of heretics.’’
In a further sign of the tensions opened up by the crisis, the Brotherhood in Alexandria accused the security forces of conspiring with ‘‘thugs’’ loyal to ElBaradei’s Dustour Party and other liberal groups that it claimed attacked the Islamists in Alexandria.
‘‘There was clear collusion by the security forces, which did nothing (to stop the attackers),’’ said Anas al-Qadi, a Brotherhood spokesman in Alexandria, according to the website of the Brotherhood’s political party.
‘‘In whose interest are the Interior Ministry and the governorate’s security director working?’’
Egypt’s security forces have been divided by the country’s turmoil, with some police in the streets showing support for anti-Morsi protesters, while others are believed to be backing the president. The crisis’ worst violence came on Dec. 5, when Brotherhood supporters attacked an opposition sit-in outside the presidential palace in Cairo, and the ensuing violence left at least 10 dead and hundreds injured on both sides.