Islamist gunmen have killed an army officer and four soldiers in an attack on a patrol near the Egyptian city of Ismailia on the Suez Canal.

The five were travelling in a pickup truck when masked gunmen in another vehicle opened fire on them.

Elsewhere a massive explosion, possibly from a car bomb, hit the security headquarters in the southern Sinai town of al Tour, killing two people and wounding 50.

Rockets were reported to have also been fired at a state satellite station in Cairo, injuring two people.

The attacks came hard on the heels of clashes in the capital Cairo between security forces and Islamist protesters on Sunday, which left 51 people dead and hundreds injured.

The deaths occurred when crowds from Egypt's two rival camps - supporters of ousted Islamist president Mohammed Morsi and backers of the military which deposed him - poured into the streets and turned on each other.

Several neighbourhoods of Cairo resembled combat zones as street battles raged for hours between the opposing factions.

Ex-president Morsi's supporters fired birdshot and firebombs at police, who responded with gunfire and tear gas.

Streets were left strewn with debris and the air was thick with teargas and smoke from burning fires.

It was the highest death toll in a single day of violence in Egypt since August 14, when security forces raided two sit-in protest camps filled with Morsi's supporters in Cairo, killing hundreds.