An Egyptian court has sentenced 183 supporters of the outlawed Muslim Brotherhood to death on charges of killing police officers, part of a sustained crackdown by authorities on Islamists.

The men were convicted of playing a role in the killings of 16 policemen in the town of Kerdasa on the outskirts of Cairo in August 2013.

The attack took place on the same day security forces violently dismantled two massive protest camps supporting ousted president Mohammed Morsi in Cairo, killing hundreds of protesters in clashes.

The court issued its preliminary verdict against 188 defendants in a mass trial in December, of which two were now acquitted while one, a minor, was sentenced to 10 years in prison.

Charges against the remaining two were dropped after the court discovered they were dead. Thirty-four of the accused were sentenced in absentia.

The verdict came after the initial sentences were sent to the grand mufti, the government's official interpreter of Islamic law, for ratification.

After the death sentences were read out, Brotherhood supporters held in metal cages shouted profanities at policemen.

The Egyptian government's human rights record has come under closer scrutiny since activist Shaimaa Sabbagh was shot dead during a Cairo protest on January 24, a day before the anniversary of the 2011 uprising that toppled Hosni Mubarak.

The interior ministry has promised an investigation.

Government continues crackdown on Brotherhood supporters

The death sentences followed one of the bloodiest attacks on Egyptian security forces in years. Islamic State's Egypt wing claimed responsibility for a series of coordinated operations that killed at least 27 people last week.

President Abdel Fattah al-Sisi blamed the Brotherhood for the violence and told Egyptians in a televised address that the war against militancy would be a long, tough one.

Egyptian authorities make no distinction between the Muslim Brotherhood, Islamic State and Al Qaeda, arguing that they have a shared ideology and are equally dangerous.

Egypt has mounted one of the biggest crackdowns in its modern history on the Brotherhood since the political demise of Morsi, the country's first democratically-elected president.

Thousands of Brotherhood supporters have been arrested and put on mass trials in a campaign which human rights groups say shows the government is systematically repressing opponents.

Mr Sisi, who as army chief toppled Morsi, has described the Brotherhood as a major security threat.

The movement said it was committed to peaceful activism.

Since the army deposed Morsi in 2103, at least 1,400 people have been killed in a police crackdown on protests.

Hundreds were sentenced to death in swift mass trials which the United Nations said were "unprecedented in recent history".

Morsi and nine others face a new espionage trial on February 15 on charges of leaking "classified documents" to Qatar and Al Jazeera television.

Reuters/AFP