The death toll from clashes between protesters and police as Egypt marked the fourth anniversary of its 2011 uprising has risen to 20, most of them Muslim Brotherhood demonstrators.

The death toll from clashes between protesters and police as Egypt marked the fourth anniversary of its 2011 uprising has risen to 20, most of them Muslim Brotherhood demonstrators, AFP reported Monday.

At least 19 protesters, mostly Islamist supporters of ousted President Mohammad Mursi, and a policeman were killed, a health ministry official said.

Late Sunday, officials had put the death toll at 15, including the policeman who was shot dead during clashes in a northern Cairo district.

Tensions had surged ahead of the anniversary, and a female demonstrator was killed in clashes with police during a rare leftwing protest in Cairo on Saturday.

Another 18-year-old female protester was also killed on Friday in clashes in Alexandria.

Egypt has been gripped by political turmoil since the 2011 uprising that overthrew Hosni Mubarak, and by violent unrest since his successor Mursi was ousted.

Sisi has since led a crackdown on Mursi's supporters that has left hundreds dead.