Egyptian police have once again clashed with anti-government protesters in various cities across Egypt, following the announcement of Field Marshal Abdel Fattah el-Sisi’s presidential nomination.

Tens of anti-coup protesters were injured and arrested by security forces in the Sidi Bishr area of Egypt's northern city of Alexandria on Friday.

Police stationed themselves outside of mosques after Friday prayers when demonstrators began chanting slogans against Egyptian officials and the military-backed interim government.

Additionally, in Cairo's Maadi and Ain Shams neighborhoods, police fired tear gas at people marching against Sisi who recently announced his resignation as Egypt’s military chief to run for president.

The anti-government demonstrators also criticized death sentences handed down to roughly 500 supporters of ousted president, Mohammed Morsi, and the Muslim Brotherhood in a case related to the killing of a single police officer in the Nile Valley city of Minya.

Meanwhile, demonstrators have been holding rival rallies across cities in Egypt including Cairo, Alexandria and the Nile Delta city of Mansoura.

Earlier on Friday, attackers stormed Sisi's campaign offices in the northern city of Port Said.

Sisi was appointed as the general commander of the armed forces and defense minister by Morsi back in 2012.

Egypt has been experiencing unrelenting violence since Morsi, the country’s first democratically-elected president, was ousted on July 3, 2013.

Rights groups say at least 1,400 people have been killed in the violence since the ouster of Morsi, “most of them due to excessive force used by security forces.”