Islamists massed Saturday in a new show of force to demand the army restore Egypt's first democratically elected leader, after 24 hours of ferocious violence killed 37 people and injured more than 1,400.

Tears flowed freely as thousands of Muslim Brotherhood supporters mourned four members of the movement killed in the violence that erupted during protests against the military's ouster on Wednesday of Islamist president Mohammed Morsi.

Unidentified gunmen killed two Egyptian policemen guarding a government building in the northern Sinai town of al-Arish on Friday, a security official told Agence France Presse.

The gunmen, who were on a motorbike, shot the policemen dead before fleeing the scene, the official said.

Muslim Brotherhood supreme guide Mohammed Badie told a crowd of supporters of Egypt's ousted president Friday that protesters will remain mobilized until Mohammed Morsi's return after he was deposed by the military.

"Millions will remain in the squares until we carry our elected president, Mohammed Morsi, on our shoulders," Badie told the cheering crowd.

More than 200 Afghans staged a noisy protest in Kabul on Friday in support of ousted Egyptian president Mohamed Morsi, whose Islamist regime was thrown from power after mass demonstrations and army intervention.

The protesters took to the streets of the Afghan capital after Friday prayers, chanting pro-Morsi slogans, waving a large Egyptian flag and demanding the president's reinstatement.

Turkey's prime minister on Friday condemned the military intervention that toppled Egypt's Islamist president Mohamed Morsi as an enemy of democracy, and chastised the West for failing to brand the ouster a coup.

Referring to his country's history of coups, Recep Tayyip Erdogan warned that such military uprisings come at a heavy price and must not be tolerated.

Ismail Haniya, head of the Hamas government in Gaza, appealed in a Friday sermon to have faith in the Arab Spring despite the ouster of Egypt's Islamist president Mohamed Morsi by the army.

"Do not fear for the Palestinian cause or for the resistance (against Israel) or for Gaza. Egypt is behind us, as are the Arab and Islamic countries," Haniya said.

Running clashes erupted on Friday evening between supporters and opponents of Egypt's ousted Islamist president Mohamed Morsi near Cairo's Tahrir Square.

The sound of gunfire could be heard as the two sides hurled rocks at each other on the October 6 bridge leading into Tahrir. Below the bridge, ambulances were ferrying the injured out of the area.

The African Union suspended Egypt from the continental body Friday after the ouster of president Mohammed Morsi, in line with its strict rules against unconstitutional changes of government.

The AU's Peace and Security "council decided to suspend the participation of Egypt in AU activities until the restitution of constitutional order", said an official statement.

World Bank chief Jim Yong Kim said Thursday he hopes Egypt's loan and assistance program will continue despite the ouster of Islamist president Mohamed Morsi, but called for progress toward new elections "as quickly as possible."

"We are in the middle right now of trying to understand just what did happen and what the legal status is of the government in place," Kim said at a press conference at Chile's government palace, after he met with President Sebastian Pinera.

An Egyptian soldier was killed early Friday in coordinated rocket and machinegun attacks by Islamist militants on army checkpoints and a police base in the restive Sinai, medics said.

The soldier was killed when the militants fired on an army checkpoint near the north Sinai village of al-Gura, medics said, adding two other soldiers were wounded in the attack.