The United Nations has warned of an influx of refugees fleeing to Sudan's neighboring countries, as the fighting continues between the country's top military generals.

UN High Commissioner for Refugees Filippo Grandi said late on Monday that the UN refugee agency (UNHCR) was bracing, alongside governments and partners, "for the possibility that over 800,000 people may flee the fighting in Sudan for neighboring countries."

"We hope it doesn’t come to that, but if violence doesn’t stop we will see more people forced to flee Sudan seeking safety," Grandi said on Twitter.

Witnesses in Khartoum reported air strikes, gunfire and explosions, despite a second extension of a 72-hour cease-fire.

The power struggle between Sudan's de facto leader, army chief Abdel Fattah Burhan, and his former deputy Mohammed Hamdan Dagalo (more commonly known as Hemeti) who commands the powerful Rapid Support Forces paramilitary group is well into its third week.

The fighting has killed over 500, with thousands more injured. At least 75,000 Sudanese citizens have been internally displaced, with over 50,000 crossing overland into neighboring countries, as per UN figures.

Russia evacuates more than 200 people from Sudan

Russia's Defense Ministry said on Tuesday it was evacuating more than 200 people from Sudan.

"Four Il-76 aircraft ... of the Russian Aerospace Forces are bringing more than 200 people from the Republic of Sudan to the Russian Federation," the ministry said on the Telegram messaging app.

The evacuees were citizens of Russia and neighboring countries, it added.

Nearly 500 evacuated to Saudi Arabia by sea

Saudi Arabia announced late on Monday it was evacuating a further 212 individuals from Sudan via the Red Sea, including US and British citizens.

The Saudi Foreign Ministry said the latest evacuation mission included 41 Saudi nationals and 171 foreign nationals.

The latter included citizens of Afghanistan, the Philippines, the Comoros Islands, Sri Lanka, Ukraine, Madagascar, Syria, the UK and the US.

Monday's ship brings the total of those Saudi Arabia has evacuated since the conflict erupted to 5,409, the ministry said. They include 225 Saudi nationals.

Earlier on Monday, a US-operated rescue ship carrying 300 civilians fleeing Sudan arrived in Saudi Arabia. The French AFP news agency cited officials as saying the ship carried 105 US citizens, 100 Sudanese, and citizens of 15 other countries.

Analyst sees little hope for Sudan peace process

The chances of Sudan's warring generals ceasing the fighting and engaging in a meaningful peace process are low, said Jon Temin, vice president of policy and programs at the Truman National Security Project in Washington DC.

Temin, who previously served as the Director of the Africa Program at Freedom House, told DW on Monday that both Burhan and Daglo were likely to fight until one party wins.

"Both of these generals and the forces they command, they are accustomed to fighting. They are accustomed to getting what they want through fighting. And it's awfully hard to see now how they coexist. It was hard to see how they coexist even before this fighting kicked off."

Temin also cast doubt on the possibility of reaching an agreement that would satisfy both parties, but he said the hope lay in "negotiations with strong leadership from the region," alongside the US and other world powers involved.

He also dismissed the possibility of a foreign military intervention, saying he could only imagine it happening in "the rarest of circumstances."