Morocco has said that 23 people died in the June 24 incident, while Spanish authorities have argued that no deaths occurred in their territory. NGO Amnesty International said at least 37 people died and 77 others remain missing.
The report said that "many of the injured continued to be beaten and kicked as they lay on the ground, semi-conscious, unresponsive or struggling for breath."
One interviewee said that Spanish police forced injured people back across the border to Morocco. A 17-year-old Sudanese citizen said people arrested by Moroccan police were "beaten by hammers in their head until they passed away" in jail.
It also decried the lack of information concerning the identity of the deceased and the fate of the missing.
"Moroccan and Spanish authorities failed to provide prompt and adequate medical assistance to the injured, including by denying a Red Cross ambulance team access to the area, while dozens were left unattended in the full glare of the sun for at least eight hours," Amnesty said.
The handling of the mass border crossing attempt on June 24 between Morocco and Spain's North African enclave of Melilla remains a high-stakes political headache for the Spanish government.
The incident has been heavily criticized by Spain's ombudsman and U.N. human rights experts. The country's interior minister has been repeatedly grilled in parliament and has faced calls to resign from opposition parties.
