Egypt\'s government on Tuesday began probing clashes which killed 25 people, mostly Coptic Christians, amid mounting anger at the ruling military council and calls for the prime minister to resign.

Egyptian Coptic men carry the coffin of a victim of Sunday\'s deadly clashes with security forces during a funeral at Abassaiya Cathedral in Cairo, October 10.

The ruling Supreme Council of the Armed Forces had tasked Prime Minister Essam Sharaf\'s government to immediately form a fact finding panel to investigate clashes Sunday in central Cairo, which killed 25 people and left over 300 injured.

Political and religious leaders spent Monday locked down in crisis talks, amid fears of widespread sectarian unrest, threatening an already fragile transition from the rule of president Hosni Mubarak.

Coptic demonstrators had taken to the streets on Sunday to denounce an earlier attack on a church in the southern city of Aswan, before the protest degenerated into violence.

State television accused the Coptic demonstrators of firing shots that killed three army troops, prompting fights between Christians and Muslims later that night.

But furious Copts said the security forces attacked the demonstrators, driving vehicles into the crowd and crushing several protesters.

New York-based rights group Human Rights Watch has called for a "prompt, thorough, and impartial" investigation, which "should specifically address the killing of at least 17 Coptic Christian demonstrators who appear to have been run over by military vehicles."

"It should also examine the role of the military and police officers in the violence," HRW said in a statement.

Thousands of people attended a service at the Coptic cathedral in Cairo late on Monday for the funerals of 17 demonstrators.

Live television showed the coffins being brought in a procession from the Copt hospital in downtown Cairo where autopsies were carried out.

The coffins, each bearing the victim\'s name and flowers arranged in a cross, were lined up in the cathedral for the funeral service before being taken out for burial.

Earlier on Monday, hundreds had gathered outside the Coptic Hospital, chanting against the military council and its head Field Marshal Hussein Tantawi, who took power when Mubarak was ousted in February.

"SOS: Copts under attack from the army of Egypt," read one banner.

Copts complain of systematic discrimination, but since Mubarak\'s fall, tensions have also mounted between the military -- initially hailed for not siding with Mubarak -- and groups which spearheaded the revolt.

Military prosecutors began questioning 25 people accused of involvement in the clashes.

Egypt\'s Coptic Orthodox Church led by Pope Shenuda III accused "infiltrators" of triggering the street battle on the Nile waterfront.

Grand Imam Ahmed al-Tayyeb, the country\'s top Muslim official who chaired a meeting of religious leaders, urged the cabinet to swiftly issue a unified law on building worship places, in a bid to ease sectarian tension.

The cabinet vowed on Monday to look into amending religious laws which would give Copts more guarantees to freedom of worship.

But after months of tensions, unrest and clashes, some say the measure is too little too late.

On Tuesday, leading independent daily Al-Masry Al-Youm called for the resignation of the prime minister in a front page editorial.

"The state has lost its stature, the regime is on the verge of collapse, and Sharaf\'s government has run out of credit. All that is left to say is Sharaf, resign."

The liberal Wafd party\'s mouthpiece, echoed the view.

"After what has happened, we can say that he cannot serve as a prime minister and he must leave his post."

International calls for restraint poured in, as the Arab world\'s most populous nation teetered on the edge of widespread unrest, and activists feared their revolution was crumbling.

Saudi Arabia called on Egypt to exercise restraint in the face of the violence.

"We are watching these latest developments with pain and grief," said a statement posted late Monday on the official Saudi news agency SPA.

"Saudi Arabia calls on all our brothers in Egypt to exercise restraint...(and ensure) the unity, stability, and prosperity" of the country."

White House spokesman Jay Carney said US President Barack Obama was "deeply concerned" about the violence.

A "deeply saddened" UN Secretary General Ban Ki-moon urged the Egyptian military authorities to defend "all faiths" in the country, while European leaders in Luxembourg expressed alarm at the Cairo clashes.

The Congregation for Eastern Churches at the Vatican slammed the "senseless violence", with Cardinal Leonardo Sandri telling Vatican Radio he hoped it "would not lead as well to a climate of precariousness and difficulty" for Copts.