At least 42 people were killed on Monday when Islamist demonstrators enraged by the military overthrow of Egypt's elected President Mohamed Mursi said the army opened fire during morning prayers at the Cairo barracks where he is being held.

CAIRO, July 8 (Reuters) - Egypt's Muslim Brotherhood and its Islamist allies called for more protests on Tuesday, after 51 people were killed in Cairo on Monday when the army opened fire on supporters of ousted Islamist President Mohamed Mursi.

Egypt's Strong Egypt Party on Monday called on Muslim Brotherhood leaders to stop escalating against the Egyptian army, going on to blame the army for not preventing bloodshed as promised.

Jihadi groups in Sinai threatened a "severe retaliation" to the clashes that erupted at the Republican Guard headquarters on Monday that led to the killing of 42 people.

The Muslim Brotherhood denied on Sunday that its Supreme Guide Mohamed Badie has made a deal to withdraw demonstrators in exchange for Mohamed Morsi's release and reinstatement as president

Mass demonstrations have filled Tahrir Square as more begin to converge on the presidential palace. The demonstrators are protesting the Muslim Brotherhood and the group's demand to reinstate ousted president Mohamed Morsi

Hamas called on Egypt Sunday to reopen the Rafah border crossing, which has been closed for three consecutive days.

Egypt's political transition after President Mohamed Mursi was ousted by the military stumbled at the first hurdle, after the choice of liberal politician Mohamed ElBaradei as interim prime minister was thrown into doubt by Islamist objections.

Violence broke out in Luxor on Friday, following a fight between a group of Christians and a single Muslim man, who died of his injuries, according to state-owned Al-Ahram.

The pro-Morsi National Alliance in Support of Legitimacy stressed in a Thursday press release that ousted president Mohamed Morsi is still the legitimate ruler of the country, describing his overthrow on Wednesday as a "military coup."

An alliance of Islamist parties and movements including ousted president Mohamed Morsi's Muslim Brotherhood has called for "peaceful protests" on Friday to denounce the military's overthrow of the Islamist president.

A number of Islamist channels actively supporting ousted president Mohamed Morsi promptly went off-air following an announcement Wednesday night that Morsi would be removed from office.

Egypt is braced for further dramatic events on Friday as the vanquished Muslim Brotherhood called for a "day of rejection" following a widespread crackdown on its leadership by the country's new interim president, Adly Mansour.

Several explosions were heard Thursday night in the Israeli Red Sea resort of Eilat near the Egyptian border, a police spokesman said, adding that the source of the blasts was not known.

The Muslim Brotherhood-owned television channel Misr 25 went off air along with several other Islamist-run channels, including the controversial Hafez and Al-Nas, shortly after the military statement announcing the ouster of president Mohamed Morsi.

Egyptian security forces on Wednesday arrested two senior leaders of the Muslim Brotherhood close to ousted president Mohamed Morsi, security officials said.

Brotherhood spokesperson Ahmed Aref on Wednesday evening denied the arrest of Supreme Guide Mohamed Badie.

The Muslim Brotherhood preemptively denied on Tuesday involvement in attacks “likely” to break out against opposition protesters at Tahrir Square and the presidential palace.

The Muslim Brotherhood issued a statement on Tuesday warning of attacks planned against anti-Morsi protesters at Tahrir square and Ittihadiya presidential palace.

Posters of Mohamed Morsi can be seen on every other Egyptian street this week, usually with the eyes gouged out and his face covered with a giant cross. But outside the Rabaa al-Adaweya mosque in Nasr City, in east Cairo, pictures of the president remain in rather better shape.

The National Salvation Front (NSF) praised the armed forces’ Monday announcement for not abandoning the Egyptian people and protecting the nation, in a statement issued Monday morning.