Egyptian troops were deployed across Cairo on Friday with the streets almost deserted as residents braced for new Islamist protests, just two days after nearly 600 people were killed.

Soldiers manned roadblocks on major thoroughfares, closing off some of them with armored personnel carriers as supporters of ousted president Mohammed Morsi called for a "Friday of anger".

Egypt's army and police will deal firmly with any violation of the law, state television reported.

At least 623 people died and thousands were wounded on Wednesday when police cleared out two protest camps in Cairo set up to denounce the military overthrow on July 3 of Egypt's first freely elected president, Islamist leader Morsi.

It was the third mass killing of Morsi's supporters since his ouster. The assault left his Muslim Brotherhood in disarray, but it said it would not retreat in its showdown with army commander General Abdel Fattah al-Sisi.

"After the blows and arrests and killings that we are facing, emotions are too high to be guided by anyone," said Brotherhood spokesman Gehad El-Haddad.

Residents of some areas formed their own roadblocks, checking identity papers and searching cars.

The international community expressed grave concern, with the president of the UN Security Council pleading for "maximum restraint" after an emergency meeting on the violence.

The European Union said top officials would hold an emergency meeting on the situation in Egypt, where the army-installed government has imposed a nationwide state of emergency and night-time curfews in 14 provinces.

Sporadic violence continued throughout the country in the form of attacks on security personnel, with 13 killed in the Sinai Peninsula in 24 hours.

Gehad al-Haddad, a Muslim Brotherhood spokesman, announced Friday's marches on his Twitter account.

"Anti-coup rallies ... will depart from all mosques of Cairo and head toward Ramsis Square after (noon) prayer in 'Friday of Anger'," he wrote.

Laila Moussa, a spokeswoman for the Anti-Coup Alliance of Islamist groups opposing Morsi's ouster, said similar protests were planned across the country.

She said Morsi loyalists, including at least two former members of parliament, had been arrested in dawn raids ahead of the protests.

On Thursday, Tamarod, the protest group that organized opposition to Morsi's rule, also urged Egyptians to take to the streets.

It said they should turn out on Friday "to reject domestic terrorism and foreign interference".

The international community expressed grave concern, with the EU announcing top representatives from all 28 member states would meet on Monday.

France said President Francois Hollande would discuss the crisis with British Prime Minister David Cameron and German Chancellor Angela Merkel, whose government issued a fresh condemnation of the violence.

On Thursday, the UN Security Council held an emergency meeting on Egypt, with its president, Argentine ambassador Maria Cristina Perceval, calling for an end to the violence and underlining the need for "national reconciliation".

US President Barack Obama said on Thursday that Washington was canceling a joint US-Egyptian military exercise.

"While we want to sustain our relationship with Egypt, our traditional cooperation cannot continue as usual when civilians are being killed in the streets and rights are being rolled back," he said.

The US State Department warned citizens not to travel to Egypt and called on those already there to leave.

Egypt's presidency responded defiantly to Obama's remarks, warning that "statements not based on facts may encourage violent armed groups".

"The presidency appreciates US concern for developments in Egypt, but it wished it could have clarified matters," said the statement carried by the official MENA news agency.

AFP-Reuters