Spain and Morocco were accused Friday of covering up the deaths of dozens of migrants and refugees at a Spanish enclave last year.
U.K.-based international rights group Amnesty International said both countries failed to properly investigate the events at Melilla.
On June 24, 2022, around 2,000 Sub-Saharan African migrants and refugees attempted to enter Spain's North African enclave from Morocco. At least 37 died and at least 76 are still missing, the nongovernmental organization (NGO) said.
Morocco said 23 people died in a crush when migrants fell from the fence, and Spain has said no deaths occurred on its soil.
"One year on from the carnage at Melilla, Spanish and Moroccan authorities not only continue to deny any responsibility but are preventing attempts to find the truth," said Amnesty International's Secretary General, Agnes Callamard.
Amnesty said authorities had failed to make any attempt to repatriate victims' remains and had not provided a full list of names and causes of death, as well as CCTV footage which could inform an investigation.
"The lessons of Melilla must be learned or - as the shipwreck off the Greek coast shows - arbitrary loss of life, violence and impunity at borders will continue," Callamard added.
A fishing boat packed with hundreds of migrants sank off Greece's south-west coast earlier this month, on a journey that started from Libya and was supposed to end in Italy. At least 82 were killed and hundreds are still missing.
Spain's Attorney General investigated the Melilla incident but declined to charge Spanish officers who he said had been unaware of the fatal crush. Spanish lawmakers rejected calls for a parliamentary inquiry.
The handling of the event by authorities on both sides of the border was criticized however by rights groups and independent investigators.
Spain's ombudsman said Spain had returned those who jumped the fence without processing their cases and the U.N.'s Commissioner for Human Rights said they found "no genuine and effective access to asylum at the border."
A spokesman for Spain's Interior Ministry said the investigation by Spain's Attorney General had been carried out "with full guarantees and in full depth."