Violence in Sudan’s Darfur region shows “the hallmarks of ethnic cleansing and may amount to crimes against humanity,” UK foreign minister David Lammy said.

Lammy called on the army and the paramilitary Rapid Support Forces (RSF) to “de-escalate urgently” and said in a statement issued late Thursday that Britain would continue to “use all tools available to us to hold those responsible for atrocities to account”.

Paramilitary shelling of the besieged city of El-Fasher, the state capital of North Darfur, has killed more than 30 civilians and wounded dozens more, activists said on Monday.

El-Fasher is the last major city in the vast Darfur region that still remains in army control.

Lammy said that reports of the violence in and around El-Fasher were “appalling”.

“Last week, the UK gathered the international community in London to call for an end to the suffering of the Sudanese people.

“Yet some of the violence in Darfur has shown the hallmarks of ethnic cleansing and may amount to crimes against humanity,” he said.

He called on the RSF to “halt its siege of El-Fasher”, adding that “the warring parties have a responsibility to end this suffering.”

Lammy also urged the Sudanese Armed Forces to allow safe passage for civilians to reach safety.

International aid agencies have long warned that a full-scale RSF assault on El-Fasher could lead to devastating urban warfare and a new wave of mass displacement.

UNICEF has described the situation as “hell on earth” for at least 825,000 children trapped in and around El-Fasher.