Details added, title changed (the first version was posted at 21:17, 6 October 2013)
At least 44 people were killed and more than 240 injured in Egypt on Sunday in clashes involving backers of ousted Islamist president Mohammed Morsi, his opponents and security forces, said a health official, dpa reported.
Twenty-four were killed 24 in Cairo, 15 perished in nearby Giza and five died in the southern provinces of Beni Sueif and al-Minya, Khaled al-Khatib, the director of the Health Ministry's Emergency Services, told the state-run news agency.
The clashes erupted as followers of Morsi's Muslim Brotherhood and supporters of the army, who deposed the Islamist leader in July, held rival rallies on Sunday that marked national Army Day and the 40th anniversary of the Egyptian-Israeli war.
As the army's backers packed central Cairo's Tahrir Square, pitched street battles raged for hours between Morsi's supporters and security forces in the nearby Ramsis Street.
The Interior Ministry, which is in charge of police in Egypt, accused the Brotherhood followers of rioting and "seeking to disrupt Egyptians' celebrations."
Police arrested more than 400 Brotherhood followers, including 25 for allegedly possessing 51 homemade explosive devices, according to state media.
State television reported that security forces had foiled two attempts by Morsi's supporters to storm Tahrir Square.
Armoured personnel carriers mounted with machine guns were deployed on approaches to Tahrir, which was closed off with barbed wire and barricades.
Army helicopters flew over the area as people chanted pro-army slogans and waved the national flag. Other celebrants in the square carried pictures of Army Chief and Defence Minister Abdel-Fattah al-Sissi, the architect of Morsi's ouster.
Metal detectors were also installed at entrances to the Square to prevent weapons from being smuggled in.
The Brotherhood, meanwhile, held al-Sissi and Interior Minister Mohammed Ibrahim responsible for the killings and called for an international inquiry.
"We appeal to all rights organizations and to all free and honest people in the world to condemn these crimes and to endeavour to halt bloodshed," the Brotherhood's Freedom and Justice Party said in a statement on its website.
Hundreds of people have been killed in Egypt since the army toppled Morsi on July 3 following massive street protests against his rule.
Morsi's Brotherhood and Islamist allies have denounced the ouster of Egypt's first democratically elected president as a coup and vowed to continue protesting until he is reinstated.
Meanwhile, two Canadians, arrested in Cairo during clashes between Morsi's backers and police in mid-August, were released from custody after prosecutors concluded they had not been involved in the violence, Wael Hussein, the northern Cairo chief prosecutor, said Sunday.
Emergency physician Tarek Loubani and film-maker John Greyson were on their way to the Palestinian Gaza Strip for a relief project when they were arrested after assisting and filming in a field hospital set up by pro-Morsi demonstrators, according to their account.