Forty bodies have been pulled from the River Nile in the Sudanese capital Khartoum following a violent crackdown on pro-democracy protests, opposition activists said on Wednesday.
Doctors linked to the opposition said the bodies were among 100 people believed killed since security forces attacked a protest camp on Monday.
Reports said a feared paramilitary group was attacking civilians.
Sudan’s ruling Transitional Military Council (TMC) vowed to investigate.
Residents in Khartoum told the BBC they were living in fear as members of the Rapid Support Forces (RSF) roamed the streets. The paramilitary unit – formerly known as the Janjaweed militia – gained notoriety in the Darfur conflict in western Sudan in 2003.
“Forty bodies of our noble martyrs were recovered from the river Nile yesterday,” the Central Committee of Sudanese Doctors said in a Facebook post.
An official from the group told the BBC that they had witnessed and verified the bodies in hospitals and that the death toll now stood at 100.
A former security officer quoted by Channel 4’s Sudanese journalist Yousra Elbagir said that some of those thrown into the Nile had been beaten or shot to death and others hacked to death with machetes.
“It was a massacre,” the unnamed source said.
On Wednesday the head of Sudan’s military council, General Abdel Fattah al-Burhan, apologised for the loss of life and called for resumed negotiations – reversing a statement the previous day in which he said dialogue was over.
A Sudanese alliance of protestors and opposition groups rejected the invitation to resume talks. One of its leading members said the military could not be trusted.
There was speculation that Gen Burhan’s about face was linked to a statement by Saudi Arabia – a key ally of Sudan’s military rulers – which called for a resumption of dialogue.
The Saudi statement came after the US state department voiced concerns over the violence in Sudan to the kingdom’s deputy defence minister, Khalid Bin Salman, and stressed the importance of a transition to a civilian-led government.
What is happening in Sudan?
Demonstrators had been occupying the square in front of the military headquarters since 6 April, days before President Omar al-Bashir was overthrown after 30 years in power.
Their representatives had been negotiating with the TMC and agreed a three-year transition that would culminate in elections. But on Monday, forces swept in and opened fire on unarmed protesters in the square.
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On Tuesday, Gen Burhan, the head of the Transitional Military Council (TMC) announced that negotiations with protesters were over, all previous agreements were cancelled, and elections would be held within nine months. Demonstrators had demanded a longer period to guarantee fair elections and to dismantle the political network associated with the former government.
International condemnation of the crackdown was swift and on Wednesday Gen Burhan made another televised speech in which he said the TMC was willing to resume negotiations.
“We regret the events,” he said, without elaborating.
A TMC spokesman later said an investigation into the deaths of protesters had been launched.