Shaima al-Sabbagh, 32, was hit in the head as police fired birdshot ammunition, a supposedly non-lethal alternative to shot gun pellets, into the crowd to disperse the march.

Ms al-Sabbagh, the mother of a five-year-old boy, was shot while she marched towards the Tahrir Square to lay a commemorative wreath on the eve of the anniversary of the 2011 uprising against Hosni Mubarak.

Ms al-Sabbagh, from Alexandria was taken to a hospital where she was declared dead on Saturday. 

Videos posted online show Ms al-Sabbagh in a group of protesters carrying placards and chanting 'bread, freedom and social justice' - the chief slogan of the 2011 uprising.

Ms al-Sabbagh, a member of the Socialist Popular Alliance Party who organised the peaceful march on Saturday, was photographed the moment she was hit.

Prime Minister Ibrahim Mahlab said al-Sabbagh's death was being investigated and vowed that 'whoever committed a mistake will be punished, whoever he may be.'

The prominent Hisham Mubarak Law Center said in a Facebook post that five of Ms al-Sabbagh's fellow protesters who had given investigators their account of the incident were charged with assaulting police and taking part in an illegal demonstration.

The interior ministry said it was investigating the death, but suggested Islamist 'infiltrators' were to blame. 

The Socialist Popular Alliance Party released a statement on Sunday, blaming Cairo police for  Ms al-Sabbagh's death.

Today marks the fourth anniversary of the 2011 uprising against Hosni Mubarak as part of the Arab Spring.

By Sunday afternoon, Egyptian security officials said clashes between police and Islamist protesters in an eastern Cairo district have left nine demonstrators dead, taking the total death toll to 11.

They say the Sunday clashes in the Matariyah area also injured 13.

Authorities had tightened security in Cairo and other cities ahead of today's anniversary after Islamists called for protests against the government of President Abdel Fattah al-Sisi, the former army chief who ousted Islamist president Mohamed Morsi in 2013. 

Sunday's anniversary of the uprising against Mubarak is a test of whether Islamists and liberal activists have the resolve to challenge Egypt's U.S.-backed government once again.

As mourners gathered for Ms al-Sabbagh's funeral, police shot and killed 'an armed pro-Muslim Brotherhood protester' in Alexandria.

The man has been 'shooting randomly with an automatic rifle while marching with a number of pro-Muslim Brotherhood supporters in Alexandria's Al-Awayed district,' Egyptian media reports.

Police also arrested another man with an automatic rifle, also in the march, along with two men who had Molotov cocktails,according to an interior ministry statement. 

Security forces have been stamping out dissent since the army ousted president Mohamed Mursi of the Muslim Brotherhood in July 2013 after mass protests against his rule. 

Dozens of protesters were killed during last year's anniversary of the revolt centred in Cairo's Tahrir Square. 

Separately, a bomb targeted policemen stationed outside a Cairo sports club, the sources said.

In the Nile Delta region of Baheira, about 170 km (104 miles) from Cairo, two militants were killed when bombs they were planting exploded, state television reported.

In Cairo, riot police backed by soldiers in armoured vehicles sealed off strategic roads, including ones leading to Tahrir Square.

(dailymail.co.uk)