A rights group on Saturday accused Morocco's security forces of using "unjustified" violence against migrants trying to force their way through a border fence between the North African country and the Spanish exclave of Melilla.
Morocco said 18 migrants died on its side of the fence on Friday.
What has the rights group alleged?
Amin Abidar, a spokesperson for the Moroccan Association of Human Rights (AMDH), said the migrants had been "mistreated" by Moroccan security forces during the border rush.
He described how migrants had been left trapped on the ground for hours without medical assistance.
AMDH shared videos on social media that purportedly showed dozens of migrants, some bleeding and lying motionless on the ground, with Moroccan security forces standing over them.
The rights group said the lack of action by security forces likely led to many more deaths.
Abidar told DPA news agency that the final death toll was likely to be much higher and called on Moroccan authorities to hold an "urgent and fair investigation" into the incident.
Five other rights groups in Morocco and Spain backed up the call for a probe.
The Spanish Commission for Refugees (CEAR) described what it said was "the indiscriminate use of violence to manage migration and control borders."
It said that the violence had stopped eligible asylum seekers from reaching Spanish soil.
Amnesty International's Spain director Esteban Beltran said "although the migrants may have acted violently in their attempt to enter Melilla, when it comes to border control, not everything goes."
What happened at the Morocco-Melilla border?
Early on Friday morning, around 2,000 people attempted to storm the border fence but were stopped by security forces on either side of the barrier, a government official in Melilla said.
A Spanish police source told Reuters that the migrants had attacked border guards with sticks, knives and acid.
The source said the migrants had used a different tactic to enter Melilla.
"Before they used to spread along the whole length of the fence. Now they concentrate on the part where they think it is weakest," the police added.
In addition to 18 people losing their lives, Morocco's state news agency MAP said dozens of migrants and 140 members of the security forces were injured on its side of the border.
No one died on the Spanish side, but 57 migrants and 49 police officers were injured, the Melilla official said.
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Melilla officials said over 500 migrants made it across the border after the fence was cut with shears.
Footage posted online showed a group of mainly young men, running through the streets of Melilla singing and dancing, before heading to an emergency reception center.
What was the reaction from Morocco and Spain?
The Moroccan Interior Ministry accused the migrants of using violence during the border fence storming.
It said that most were crushed to death in the "stampede."
A Moroccan official said that some of the migrants fell from the top of the barrier.
Spanish Prime Minister Pedro Sanchez condemned the "violent assault" by migrants which he called an "attack on the territorial integrity" of Spain.
"if there is anyone responsible for everything that appears to have taken place at that border, it is the mafias that traffic in human beings," Sanchez added.
On Friday, Sanchez had praised officers on both sides of the border for fighting off "a well-organized, violent assault."
Melilla, along with fellow Spanish exclave Ceuta, are the European Union's only two borders with the African continent.
In recent years, both towns have regularly seen dramatic border incidents involving migrants trying to reach the bloc.
Thousands of people, mainly from sub-Saharan Africa, often wait close to the borders for a chance to enter the EU.
mm/dj (AFP, AP, dpa, Reuters)
