The leader of Sudan's paramilitary Rapid Support Forces (RSF) has declared an investigation into what he called violations committed by his soldiers during the capture of el-Fasher.

The announcement by Gen Mohamed Hamdan Dagalo, known as Hemedti, came after escalating reports of civilian killings following the RSF takeover of the city in the Darfur region on Sunday.

He spoke after international outrage about reports of mass killings in el-Fasher, apparently documented by his paramilitary fighters in social media videos.

The RSF has since released footage which they say shows the arrest of a fighter accused of carrying out executions in el-Fasher.

Footage previously verified by BBC Verify showed the man, who goes by the name Abu Lulu online, shooting unarmed people in an area outside el-Fasher.

The video posted by the RSF on Wednesday evening - which BBC Verify has geolocated to Shala Prison on the outskirts of el-Fasher - showed fighters leading the man under guard from a pick-up truck and into a jail cell.

But the UN's top humanitarian official, Tom Fletcher, has said the RSF's assurance that it will protect civilians is at odds with the appalling news coming out of the region.

There must be accountability for those carrying out the killing and the sexual violence, he emphasized.

Earlier British Foreign Office Minister Stephen Doughty said the UK had called for an emergency meeting to address the unconscionable suffering, especially among women and girls.

The Security Council has issued a statement condemning the assault on el-Fasher, calling for safe passage for those trying to flee the city and reiterating that it will not recognize the RSF's parallel government.

Hemedti expressed regret for the suffering in el-Fasher and acknowledged violations committed by his forces, which would be investigated by a committee sent to the city.

However, observers note that past promises to investigate similar accusations, particularly in relation to violence in el-Geneina in 2023, have not materialized.

The UN has expressed shock at reports that more than 460 civilians were killed at a hospital in el-Fasher during the RSF takeover.

Meanwhile, analysts suggest that international military support to the RSF, allegedly provided by the UAE, must be scrutinized.

The RSF's control over el-Fasher signifies a growing division in Sudan, with the rival army in control of the capital, Khartoum, and eastern regions.