Fighters calling themselves Sinai Province clash with patrol boat in Mediterranean off Gaza Strip, military says.
Six people have been killed in clashes between anti-coup protesters and Egyptian police in a city adjacent to Cairo, the health ministry said.
Supporters of ousted Islamist president Mohamed Morsi had held small marches in Giza after the Friday morning prayers for Eid al-Fitr, which marks the end of the holy Muslim fasting month of Ramadan.
State news agency MENA quoted an interior ministry source as saying security forces intervened and arrested 15 armed Muslim Brotherhood members.
Anadolu News Agency reported several protests in the Giza neighbourhoods of al-Haram, Nahra and al-Omraniya following the prayers, adding that security forces responded by firing live bullets.
In the city of Alexandria, in the country’s north, security forces used tear gas and water cannon to disperse protesters, sources there told Al Jazeera.
Protests by the outlawed Muslim Brotherhood have largely faded under a tough security crackdown, but smaller rallies are held regularly by Egyptians protesting against the coup that removed Morsi from power in 2013.