More than 70 people have been killed following a drone strike on a mosque in Sudan's Darfur region, a senior medical source has told the BBC. Friday's attack in the city of el-Fasher has been blamed on the paramilitary Rapid Support Forces (RSF), but the group has not taken responsibility.

The RSF and the army have been engaged in a ferocious civil war for more than two years. The paramilitaries are gaining ground as they fight to seize complete control of el-Fasher - the last army stronghold in Darfur and home to more than 300,000 civilians who have been trapped by the fighting.

One resident told the BBC the drone struck during morning prayers, killing dozens of people instantly. The medical source stated that 78 died and about 20 were injured, but the process of extracting the bodies from the rubble of the building was still ongoing.

BBC Verify has authenticated footage showing around 30 bodies wrapped in shrouds and blankets next to the mosque. This week the RSF launched a renewed offensive on El Fasher, which it has besieged for more than a year. Reports say this included fierce attacks on Abu Shouk, a camp for displaced people near the city.

According to the Yale University's Humanitarian Research Lab, satellite images suggest RSF units now control much of the camp. Also, the RSF has entered the headquarters of the Joint Forces, a collective of armed groups allied to the Sudanese army, located in a former UN compound.

These advances would place el-Fasher's airport and the army's division headquarters within direct RSF firing range. Analysts warn that if the city falls to the RSF, it would solidify the group's control over western Sudan, threatening the civilians remaining there including those from ethnic groups viewed as adversaries by the RSF. A recent United Nations report has highlighted the increasing ethnic nature of the conflict, with both sides retaliating against communities associated with their opponents.

Despite the denials from RSF regarding accusations of ethnic cleansing, NGOs like Doctors Without Borders have reported plans by RSF troops to 'clean El Fasher' of its non-Arab community. The situation remains dire as international calls for peace and accountability grow.