CAIRO (AFP) ― Human Rights Watch on Tuesday accused top officials in Egypt of likely “crimes against humanity” in an Aug. 14, 2013 crackdown in which hundreds of protesters were killed.

Security forces stormed two sit-ins of supporters of ousted president Mohammed Morsi in Cairo’s Rabaa al-Adawiya and Nahda squares on that day, resulting in what HRW termed “one of the largest killings of demonstrators in a single day in recent history.”

A HRW report said its own investigation into the crackdown and interviews with more than 200 witnesses showed that security forces intentionally used “excessive lethal force” in breaking the sit-ins.

“The killings not only constituted serious violations of international human rights, but likely amounted to crimes against humanity,” according to the report, which HRW released to mark one year since the carnage.

HRW said its report identifies the most senior security officials and key leaders in the chain of command “who should be investigated ... including Interior Minister Mohamed Ibrahim, then defence minister Abdel Fattah al-Sisi, and Medhat Menshawy,” who led the crackdown at Rabaa al-Adawiya.

At least 817 demonstrators died in Rabaa al-Adawiya square alone, it said.

According to an AFP correspondent who was at the square, more than 100 protesters were killed several hours into the crackdown.

Police said eight policemen also died in Rabaa, from a total of 42 policemen killed across Egypt that day.

Since that day, more than 1,400 people have died in street clashes, including the Rabaa carnage, over 15,000 jailed, among them Morsi and the top leadership of his Muslim Brotherhood, and over 200 sentenced to death in speedy trials.

Last August’s crackdown was launched after thousands of pro-Morsi supporters refused to end their sit-ins despite repeated warnings by the authorities installed by then army chief and now President Sisi, who had ousted Morsi just weeks earlier.

Morsi, Egypt‘s first freely elected president, was overthrown after millions took to the streets demanding his resignation after just one year in office, accusing the Islamist of monopolising power and ruining an already dilapidated economy.

Sisi went on to succeed Morsi, becoming Egypt’s second democratically elected president after a landslide victory in a May vote.

The crackdown was not “merely a case of excessive force or poor training,”

said Kenneth Roth, executive director of HRW in the report titled “All According to Plan: The Rabaa Massacre and Mass Killings of Protesters in Egypt.”

“It was a violent crackdown planned at the highest levels of the Egyptian government. Many of the same officials are still in power in Egypt, and have a lot to answer for.”