The world's concentration on conflicts in Ukraine and Gaza Strip is rapidly increasing the likelihood of a genocide in Sudan’s Darfur, a UN expert told BBC on Friday.

"We do have circumstances in which a genocide could be occurring or has occurred," the UN Special Adviser of the Secretary-General on the Prevention of Genocide, Alice Wairimu Nderitu, told BBC's Newsday programme.

Her remarks given to BBC coincided with a new Reuters report of tens of thousands of civilians fleeing the Darfur city of al-Fashir on Thursday as rebel forces tried to capture the last government stronghold in the region.

Prior to the raids by rebel Rapid Support Forces (RSF), more than 700 deaths had been reported in 10 days by a medical charity in the city.

Nderitu said many civilians are being targeted based on their ethnicity in the besieged Sudanese city.

The situation is unfolding to a "Rwanda-like" genocide of 1994, Nderitu said, citing a UN analysis on the increasing risk factors.

"I'm calling for attention to this particular conflict. I have been trying to get my voice out but my voice is drowned out by other wars - in Ukraine and Gaza."

The military has been fighting the paramilitary RSF for more than a year, in a civil war that has killed thousands and forced millions from their homes.

Local resident Ibrahim al-Tayeb al-Faki told the BBC his sister was killed in a military airstrike that had also destroyed his home.

The 47-year-old told the BBC he had sent his three children to live with their grandfather but his house was also hit. The family is now sheltering in its ruins.

“There is no safe place in El Fasher right now,” he said.

"Increased hostilities in El Fasher have now opened a really alarming chapter in this conflict," Nderitu said.

Around 60% of the more than 100,000 inhabitant fled on Thursday, according to the Coordinating Committee for Refugees and Displaced People, which oversees camps in the region. Fighting continued in other parts of al-Fashir on Friday, locals said.

The RSF and its allies swept through four other Darfur state capitals last year, and were blamed for a campaign of ethnically driven killings against non-Arab groups and other abuses in West Darfur – accusations they have dismissed.

About half a million more people moved into al-Fashir during the ongoing war that broke out between the army and the RSF in the capital Khartoum in April 2023, as long-simmering tensions over integrating the two forces came to a head.