A Human Rights Watch report published this week states that the Egyptian military deliberately planned the deadly assault on unarmed protesters in August 2013.
At least 817 died after the attack on Muslim Brotherhood supporters as 85,000 of them protested the toppling of Brotherhood president Mohammed Mursi in Cairo.
The report is based on interviews with 122 survivors and witnesses to the Rabaa massacre.
It calls for those responsible in the military leadership to be investigated.
These include Egypt’s president Abdel Fatah el-Sisi.
At the time of the massacre el-Sisi was chief of the military and boasted that he spent “very many long days to discuss all the details”.
The executive director and another official from Human Rights Watch were arrested at Cairo airport on Sunday and deported after travelling there to present the report.