Four dead as Egypt marks third anniversary of revolution
The BBC's Catharina Moh: "Morsi supporters are being called to demonstrate against the regime and start a new revolution"
Rival demonstrations of supporters and opponents of the military-backed government took place in Cairo.Four people have been killed in clashes in Egypt as the country marks the anniversary of the 2011 uprising which ended with the overthrow of President Hosni Mubarak.
But police broke up anti-government protests with tear gas, and arrests were reported in Cairo and Alexandria.
Tensions rose on Friday amid violence which at least 18 people died.
The government has said extra security measures are in place for Saturday.
Egyptian Interior Minister Muhammad Ibrahim urged Egyptians not to be afraid to go to events marking the anniversary of the uprising.
Supporters of the military and the government have gathered in high-profile locations including Tahrir Square.
Participants waved Egyptian flags and banners showing army chief Gen Abdel Fattah al-Sisi, whom many urged to run for president.
But police dispersed anti-government protesters in Cairo and elsewhere. Security sources said four had died: one in Cairo, one in Giza and two in the southern city of Minya.
There was tight security as Egyptian security officials visited Tahrir Square on Saturday
Opponents of the military regime - both Islamist and secular - attempted to gather but were dispersed by security services using tear gas, birdshot and - one report says - live roundsfocal point of the 2011 Egyptian uprisingShortly before 06:00 GMT on Saturday, a bomb was thrown at the wall of the police training academy in the Cairo suburb of Ain Shams, reportedly injuring one person.Six people died in four bombings in Cairo on Friday, along with at least another dozen people killed in clashes with security forces.Meanwhile on Saturday, an army helicopter crashed in the restive Sinai peninsula, with an unconfirmed report that its crew of five soldiers was dead.A large explosion was reported near a police building in Suez, at the southern entrance of the Suez canal.Islamist militants have stepped up attacks on security forces in the region since Gen Sisi toppled Islamist President Mohammed Morsi in July, with hundreds killed.ArrestsThe BBC's Yolande Knell, in Cairo, says that three years on from an uprising that raised hopes of political reform in the Arab world's most populated country, rival demonstrations are showing the deep divisions.One anti-government protest on Saturday was dispersed by tear gas as it formed outside a Cairo mosque, news agency AFP said.
In several other districts, police chased anti-government protesters into side streets, firing tear gas, birdshot - as well as live rounds, said Reuters news agency.
Tensions were raised after Cairo's police headquarters suffered heavy damage in an attack on Friday
Arrests have been made in Cairo and Egypt's second city, Alexandria - not just of Islamist supporters of deposed President Morsi, but secular opponents of the military government who have also been protesting.
The Anti-Coup Alliance, led by Mr Morsi's Muslim Brotherhood, called in a statement for 18 days of protests beginning on Saturday, mirroring the 18 days of protests that led to Mr Mubarak stepping down in 2011.
The Brotherhood has been declared a "terrorist organisation" and accused by the interim government of being behind a string of violent attacks in recent months, which the Brotherhood denies.
It condemned Friday's bomb blasts - with an Al-Qaeda-inspired militant group - Ansar Beit al-Maqdis (Champions of Jerusalem) - saying it was behind the most deadly blast at the city's police headquarters, which killed four and wounded at least 76, leaving a huge crater in the street.
But an angry group gathered outside the police headquarters after the blast, accusing the Brotherhood of being behind Friday's attacks, with some shouting "Death to the Muslim Brotherhood".
Many now expect Gen Sisi to run for president, putting a military strongman back in charge in Egypt, as was the case for the six decades leading up to 2011.
Are you in Egypt? Are you involved in the protests? You can send us your experiences using the form below.
