The human rights watchdog, known as AMDH, said at least 27 people, mostly from Sudan, South Sudan and Chad, died in the attempt, with that number likely, to rise as many more suffered severe injuries and 64 people remained missing.
The Moroccan authorities, however, had announced 23 fatalities in the border assault on June 24.
The report said around 1,500 migrants and asylum-seekers departed that day from nearby forests and arrived at the BarrioChino crossing area, which separates the Moroccan city of Nador from Melilla. There they tried to open the main gate and started climbing the checkpoints.
At that moment, the report added, Moroccan and Spanish authorities began throwing stones and smoke bombs at the migrants, causing many to die of suffocation, although autopsies have not yet been carried out. Those who tried to escape and desperately reach the fence perished in a stampede that was made worse by the heavy use of tear gas.
The report concluded that while Moroccan police did not use deadly force, some of them beat injured migrants who were laying on the ground.
In addition to the deaths, 200 Moroccan and Spanish law enforcement officers and more than 70 civilians were injured in the scuffle, the report found.
