The death toll in Egypt's rows over ousted Islamist-oriented President Mohamed Morsi rose to 75 and the number of the injured climbed up to at least 748, as fresh clashes erupted overnight Friday.

The Health Ministry said that overnight clashes that erupted Friday and continued until the early hours of Saturday rose to 75.

"The death toll of the clashes rose to 74, including nine in Alexandria and 65 near Rabia al-Adawiya Square in the capital Cairo," state-run MENA news agency quoted a Health Ministry official as saying, noting at least 748 others were injured.

Earlier on Saturday, another person was killed in clashes between Morsi's loyalists and opponents in Fayoum governorate southwest of Cairo.

However, the Muslim Brotherhood's Freedom and Justice Party said earlier Saturday in a statement posted on its official website that at least 200 people were killed and more than 4,500 others wounded, most of whom suffered gunshot wounds, in confrontations in the Nasser Street in Cairo.

The statement quoted Hisham Ibrahim, the hospital field's manager in al-Adaweya mosque, as saying that most of the cases were shot in the head, neck and chest by snipers, and they were facing a "shortage in medicine due to the heavy casualties."

The police forces started to shoot at the pro-Morsi sit-ins at 2:00 a.m. local time (GMT 0000), to disperse the crowds after the later erected tents around the Memorial in Naser street, which is a military site, a Xinhua correspondent at scene said.

The hospital field's equipment is too poor to treat the severe wounded cases, eyewitnesses said, noting an 11-year-old boy was shot dead in his neck.

The police and Muslim Brotherhood (MB) have exchanged accusations over the responsibility for the deadly confrontations.

General Prosecutor Hisham Barakt ordered on Saturday forming a panel of prosecutors to conduct an investigation into the overnight bloody clashes.

The prosecution is currently counting the number of casualties, according to MENA.

Egyptian police spokesman Hany Abdel Latif said Saturday that the police "used no more than tear gas" in the clashes, denying that the police fired live bullets at protesters and claiming that Islamist protesters started the violence.

On Friday, millions of Egyptians in Cairo and other governorates rallied in support of chief of the Armed Forces and Defense Minister Abdel-Fattah al-Sisi to show the popular approval of the security crackdown on extremism and terrorism.

In contrast, throngs of Morsi's supporters held various rallies in the country, demanding the return of Morsi and labelling his overthrow "a military coup against legitimacy."

Egyptian Interior Ministry said Friday that protests went on peacefully in Cairo and Alexandria until Morsi's loyalists, particularly the MB group, "sought to spoil these events."

"Seeking to create a crisis in Cairo, the MB organized a march from Rabia al-Adawiya Square to 6th of October Bridge and attempted to impede traffic on the vital bridge," said Interior Ministry spokesman General Hani Abdel-Latif.

He said the protestors burned tires until they clashed with residents of nearby Mansheyet Nasser neighborhood, and the security men interfered to prevent the closure of the bridge and cease the clashes.

He reiterated that the police did not use live bullets to disperse the fighting sides. "No other weapons were used in these confrontations except for tear gas bombs."

The MB and other Islamist affiliates hold the security forces responsible for the tragedy.