The US has imposed sanctions on Sudanese army chief Burhan

The US government has imposed sanctions on Sudan's army chief and de facto president, General Abdel Fattah al-Burhan, the Treasury Department said.

He led one side of the 21-month civil war that killed tens of thousands, displaced more than 12 million and pushed the country to the brink of starvation.

In a brief statement, the US accused General Burhan of “destabilizing Sudan and undermining the goal of a democratic transition.”

The announcement follows reports of the killing of civilians in the central town of Wad Madani in recent days, but this was not mentioned in the statement.

Last week, Mohamed Hamdan Dagalo, the head of the paramilitary group fighting the army, was also sanctioned by the US.

The US has accused Dagalo's Rapid Support Force (RSF) of committing genocide during the conflict.

In announcing the sanctions against Burhan on Thursday, Washington said the army under his command “carried out deadly attacks against civilians”, including targeting “schools, markets and hospitals”.

The US also alleged that the military was “responsible for the routine and deliberate denial of humanitarian access, using food deprivation as a military tactic.”

In the first year of the conflict, Secretary of State Anthony Blinken said the army had committed war crimes.

General Burhan earlier ordered an investigation into allegations that his troops committed widespread atrocities after capturing the state capital of Gezira from their paramilitary rivals.

His move came after widespread concern that civilians – including foreign nationals – had been killed since the capture of Wad Madani.

Neighboring South Sudan said on Wednesday it had summoned Sudan's ambassador to protest the “loss of life among our innocent citizens”.

Wad Madani, which is 87 miles (140 km) south of the capital Khartoum, fell to the RSF about a year ago. The military regained control of it on Saturday.

The city serves as a strategic crossroads connecting several states through key supply highways. It is also the closest major city to Khartoum.

A Sudanese human rights group accused the military of going on a rampage, killing at least 13 people in Camp Taiba, a village about 20 kilometers away.

The UN's humanitarian chief in Sudan, Clementine Nkweta-Salami, said she was deeply concerned by reports of retaliatory attacks on civilians in Gezira “based on perceived affiliation or ethnicity”.

US Special Envoy for Sudan Tom Periello called the reports “appalling” and called on the military and allied groups to investigate and hold those responsible accountable.

General Burhan said he had set up a commission to investigate the alleged killings in the Taiba camp and asked it to report back within a week.

He did not comment on the concerns raised by South Sudan and whether the investigation would focus on alleged atrocities elsewhere in Gezira.

South Sudan's foreign ministry said it had received a “comprehensive report” from its embassy in Sudan “describing the unfortunate events that led to the loss of life among our innocent citizens who maintain non-combatant status”.

The military previously accused the RSF of recruiting South Sudanese as “mercenaries” to fight on their side.

Social media videos of various incidents, including one showing a plainclothes man thrown over a bridge and then shot at by a group of men, have been widely shared online.

BBC Verify has confirmed that the video was filmed on the Hantoub Bridge over the Blue Nile River.

We cross-referenced key elements in the video, including the railings and the painting on the railings, as seen in the video, with earlier videos taken on the bridge.

One of the men involved in the incident, who carries a Sudanese flag, was wearing clothing with a logo used by the al-Baraa bin Malik Brigade, which is fighting alongside the Sudanese army in Khartoum and neighboring countries.

Two other videos taken elsewhere show at least 30 bodies of men in civilian clothes lying on the ground against a wall.

BBC Verify established by matching objects seen in the video with satellite imagery that the videos were shot at a location northwest of Wad Madani, just meters from where the army appears to have ambushed RSF fighters.

It is unclear how the men died and whether they were killed before the bodies were collected there.

It is also not possible to identify them, nor whether they were affiliated with any of the warring parties, as it is customary for armed fighters not to wear uniforms.

Videos of the ambush, the heavy firefight and the aftermath have also been shared.

Sudan's armed forces on Tuesday condemned what they called “individual violations” in parts of Gezira state and vowed that those responsible would be held accountable.

The RSF itself has been accused of carrying out retaliatory attacks in Gezira following the defection of its commander, Abu Akla Kaikal, in October last year.

Kaikal was heavily involved in the operation that led to the Army regaining control of Wad Madani.

Additional reporting by Yusuf Abdullahi, BBC Monitoring.