The United States is imposing sanctions on the deputy leader of Sudan's paramilitary Rapid Support Forces (RSF) over human rights abuses, the US envoy to the United Nations will announce during a trip to Chad's border with Sudan on Wednesday.

The move to target Abdelrahim Dagalo - brother of RSF commander Mohamed Hamdan Dagalo, known as Hemedti - is the highest profile use of sanctions since conflict between the RSF and Sudan's army broke out in mid-April and an apparent response to the dramatic violence seen in West Darfur, which the RSF is accused of perpetrating along with allied militias.

The RSF has denied the accusations by conflict monitors, rights groups and witnesses that it is behind the violence, while saying any of its soldiers found to be involved would be brought to justice.

Dagalo is the first official on either side to be sanctioned since the start of the war. Previous sanctions, levied on companies, also targeted the army.

He is being sanctioned "for his connection to abuses by the RSF against civilians in Sudan, including conflict-related sexual violence and killings based on ethnicity," Linda Thomas-Greenfield will tell reporters, according to prepared remarks seen by Reuters.

Thomas-Greenfield is making the announcement after meeting Sudanese refugees who have fled worsening ethnic and sexual violence in Sudan's Darfur region, which she described as "reminiscent" of atrocities 20 years ago, also in Darfur, that Washington declared a genocide.

Victims of the violence describe targeting of the Masalit ethnic group, razing of neighbourhoods, and widespread looting and rape that pushed hundreds of thousands into Chad. The International Criminal Court has announced an investigation into the violence.

War broke out in Sudan on April 15, four years after former President Omar al-Bashir was ousted by a popular uprising. Tensions between the army (SAF) and RSF, which jointly staged a coup in 2021, erupted into fighting over an internationally-backed plan to transition to civilian rule and integrate their forces.

PERSONALISED COMMAND STRUCTURE

In the capital Khartoum, the RSF has been accused of widespread looting, and, along with the army, of firing missiles into residential areas.

The US measures freeze any assets held by Abdelrahim Dagalo in the United States and stops US citizens from doing business with him.

Unlike the Sudanese army, the RSF's command structure is highly personalised, centred on Hemedti and his close relatives and associates.

While the sanctions carry political weight, it is unclear that they would have any impact on the course of the current conflict.

The RSF has long cultivated its closest foreign ties with the United Arab Emirates and Russia.

Unlike his brother, who served as deputy to army chief General Abdel Fattah al-Burhan on the country's ruling council from 2019 until the war, Abdelrahim Dagalo carried no official position in the country's government, but he played a leading role in developing the RSF's political relationships.

Having kept a lower profile prior to the war, he appeared in video messages early in the conflict surrounded by RSF troops, calling on Sudanese army soldiers to desert.

In June, the US imposed sanctions on companies it accused of fuelling the conflict in Sudan. The US Treasury Department targeted two companies affiliated with Sudan's army and two companies affiliated with the RSF, accusing them of generating revenue from the conflict and contributing to the fighting.

A Reuters investigation in 2019 showed that Abdelrahim Dagalo was listed as owner of Algunade, a gold mining company that was sanctioned.