LONDON — The U.K. has imposed new sanctions on senior commanders of the Rapid Support Forces (RSF) amid escalating atrocities in Sudan.

The move aims at key figures accused of mass killings, sexual violence and targeted attacks on civilians in El Fasher, including Abdul Rahim Hamdan Dagalo, the RSF’s deputy leader and brother of commander Mohamed “Hemedti” Dagalo.

Three other senior RSF officers will also now face asset freezes and travel bans to the U.K.

Foreign Secretary Yvette Cooper said the sanctions sent a message that atrocities “cannot and will not go unpunished.”

While the U.K. has targeted other RSF figures before, the paramilitary group’s recent sharing of footage of their own alleged crimes has made it easier to establish the basis for sanctions.

The penalties announced Friday coincide with a fresh £21 million aid package intended to provide food, clean water, healthcare and protection for tens of thousands caught in what the U.K. government has termed the world’s worst humanitarian crisis. The administration in London has been under pressure from lawmakers to do more to stop the bloodshed.

The U.K.’s action follows the U.S. decision this week to sanction a network it says is recruiting former Colombian soldiers to fight in Sudan’s civil war, while the European Union has also targeted RSF leadership for alleged crimes in Darfur.

Sudan has been locked in a civil war for two and a half years, with the Sudanese Armed Forces pitted against the Rapid Support Forces paramilitary group, which international institutions have accused the United Arab Emirates of backing.

Since becoming foreign secretary, Cooper has sought to place particular emphasis on the conflict in Sudan and has discussed it with her U.S. counterpart Marco Rubio on several occasions.

Donald Trump signaled a new interest in ending the violence in Sudan after meeting Saudi Crown Prince Mohammed Bin Salman in November, but it’s not yet clear if that will be sustained.