Egypt's pro- and anti-Morsi protesters take to streets
Tens of thousands of demonstrators are on the streets of Egyptian cities in rival shows of force by supporters and opponents of Mohammed Morsi, ousted as president by the military last week.
Mr Morsi's supporters have gathered outside a mosque and a barracks in Cairo to demand his reinstatement.
Anti-Morsi protesters are rallying in the capital's Tahrir Square.
Mr Morsi, Egypt's first Islamist president, is in detention, along with some senior Muslim Brotherhood figures.
He was replaced on Thursday by Adly Mansour - the head of the Supreme Constitutional Court - who promised to hold elections soon but gave no date.Military planes
A quick drive around Cairo today (if such a thing were remotely possible in a city with such chronic traffic problems) would demonstrate how divided Egypt is - hopelessly so. Early images from this crisis of passionate anti-government crowds thronging Tahrir Square in central Cairo were just part of the picture. Tahrir was never Muslim Brotherhood territory. The movement didn't play a prominent role in the original 2011 uprising and has had to plant its flags elsewhere.
The built-up working class suburbs of eastern Cairo, around Nasr City, are where the Brotherhood and those who support the deposed president feel most comfortable. In and around the Rabaa al-Adawiya Mosque, tens of thousands of Brotherhood supporters gathered throughout the day, demanding the reinstatement of Mohammed Morsi, the man they regard as Egypt's only legitimate leader.
Mr Morsi's beaming image hung from buildings around the mosque as the determined but upbeat crowd chanted his name, roundly rejecting any notion that they should support a military-backed interim administration.
Thankfully, there hasn't been a repetition of Friday's violent scenes when at least 36 people were killed across Egypt but that doesn't mean there isn't tension in the air or the prospect of further clashes. With both sides demonstrating in huge numbers, there is absolutely no sign of compromise and the situation is desperately tense.
As the region and the wider world looks on, Russia's leader, Vladimir Putin, warned that Egypt was in danger of following Syria into a dangerous and divisive civil war. It was a stark warning that should be heeded by all sides in this volatile country.
The military has deployed troops in Cairo and other locations. More than 30 people were killed and about 1,000 people injured across Egypt in protests on Friday.
Mr Morsi's supporters have been camped outside the Rabaa al-Adawiya mosque in Cairo for more than a week. On Sunday, thousands marched from the mosque to the barracks of the Presidential Guard, where they believe Mr Morsi is being held.
Another group of pro-Morsi marchers have headed for the ministry of defence, reports the BBC's Quentin Sommerville, in Cairo.
Tamarod, the opposition movement whose name means "rebel" in Arabic, called on its supporters to rally in Tahrir Square and at the Ittihadiya presidential palace.
Egypt military planes flew overhead, trailing plumes of smoke in red, white and black, the colours of the national flag.
Meanwhile, a presidential spokesman has told Egyptian TV channels that business lawyer Ziad Bahaa Eldin is "very likely" to be appointed as interim prime minister.
On Friday, Egypt's state news agency said pro-reform leader Mohamed Elbaradei would be named as interim premier.
Tamarod has tweeted that it will not accept anyone except Mr ElBaradei, a Nobel laureate and former head of the UN nuclear agency, as prime minister.
However, the ultra-conservative Salafist al-Nour party is said to be unhappy with Mr ElBaradei, whom its members view as too secular.
In other developments, plain-clothes police raided the main office of al-Jazeera's Arabic TV channel in Cairo on Sunday and arrested the bureau chief.
Abdel Fattah Fayed is accused of operating an unlicensed channel and broadcasting reports that had a negative impact on national security.
Meanwhile, 11 activists have been acquitted of inciting violence and destroying public property, the Egyptian state news agency Mena reported.
The group - which included the blogger Ahmed Douma - were facing charges relating to clashes with Muslim Brotherhood supporters outside the organisation's headquarters in March.
Tamarod - which organised the recent anti-Morsi protests - had accused the ousted president of pursuing an Islamist agenda against the wishes of most Egyptians, and of failing to tackle economic problems.
The US and other Western countries have expressed concern over Mr Morsi's removal, and have called for reconciliation and speedy elections.