A Sudanese paramilitary group accused of killing thousands of unarmed civilians in an ethnically motivated massacre has agreed to a truce.

The Rapid Support Forces (RSF), which is facing mounting criticism over apparent war crimes committed by its fighters in the city of El Fasher last month, said it had agreed to a “humanitarian ceasefire” put forward by the quad countries of the US, Egypt, the UAE and Saudi Arabia.

Officials involved in ceasefire discussions say the agreement is for a three-month truce across Sudan. However, the development may be viewed by some as an attempt by the RSF to deflect attention from the El Fasher allegations.

Hours before news emerged that the group had agreed to a ceasefire, satellite images appeared to show its recruits hiding bodies in mass graves.

The ceasefire agreement is thought to have involved the RSF’s principal backer, the UAE, which has faced criticism for allegedly supplying weapons and mercenaries used in the capture of El Fasher.

The UAE denies the claims despite evidence being presented in UN reports and elsewhere.

The RSF’s decision to accept the truce is unlikely to end its 30-month war against Sudan’s army. Earlier this week, the military-aligned government indicated it would carry on fighting after an internal meeting on a US ceasefire proposal.

The ceasefire announcement arrived amid more grim updates from Darfur, the vast region of west Sudan where El Fasher is located.

A report from Yale’s Humanitarian Research Lab, which is monitoring war crimes in El Fasher, said the RSF appeared to be conducting systematic body disposal, with mass graves being dug in trenches and pits.

The extent of the massacre is not clear, although the activist group Avaaz says its Sudan team believes “tens of thousands of civilians” have been slaughtered in the city.

Prosecutors at the international criminal court said on Monday they were collecting evidence of alleged mass killings, rapes and other crimes in El Fasher. Witnesses have reported RSF fighters going house to house, killing civilians and committing sexual assaults. According to the World Health Organization, gunmen killed at least 460 people at a hospital and abducted doctors and nurses.

Efforts are being made to bring the RSF and army together for talks in Saudi Arabia aimed at a permanent peace deal.