Authorities in Egypt have tightened security in Cairo and other cities in anticipation of possible protests to mark the anniversary of the 2011 uprising that toppled autocrat Hosni Mubarak.

The stepped-up security Sunday comes a day after a female protester was shot dead in downtown Cairo while taking part in a gathering commemorating the nearly 900 protesters killed in the 2011 revolt. Activists blame the police for the death of Shaimaa el-Sabagh, a 32-year-old mother from the Mediterranean city of Alexandria. The government says it is investigating the incident.

Police have sealed off several main squares in Cairo and beefed up security at vital state installations.

Islamists opposed to the rule of President Abdel-Fattah el-Sissi say they intend to stage street protests to mark the anniversary.