The calls came amid efforts to get both the army and paramilitary Rapid Support Forces (RSF) to agree to a three-day ceasefire across the Muslim Eid that starts on Friday.

UN Secretary-General Antonio Guterres also appealed to Sudan’s warring factions to observe a ceasefire over the Muslim Eid al-Fitr holiday to allow civilians to reach safe areas as rival forces battled for a sixth day on Thursday.

All parties, including calls from the UN secretary-general, and South Sudan and Ethiopia leaders, affirmed the necessity to stop the violence and resort to dialogue.

Thousands of civilians fled out of the capital Khartoum on Thursday to a background of gunfire and explosions. Large numbers also crossed into Chad to flee fighting in the western region of Darfur.

The US said it was sending more troops to the region in the event that it decided to evacuate its embassy in Khartoum.

More than 330 people have been killed so far in the violent power struggle that broke out last weekend between two previously allied leaders of Sudan’s ruling military government.

The fiercest battles between the army and the paramilitary RSF have been around Khartoum – one of Africa’s largest urban areas – and in Darfur, still scarred by a long conflict that ended three years ago.

Guterres, speaking to reporters after meeting virtually with the heads of the African Union, the Arab League and other organisations, said, “There was a strong consensus on condemning ongoing fighting in Sudan and calling for cessation of hostilities as an immediate priority.”

Civilians trapped in conflict zones should be allowed to escape and seek medical treatment, food and other supplies, he said.

Casting blame

Sudanese army chief General al-Burhan told Al Jazeera he would support a truce on condition it allowed citizens to move freely – something he said the RSF had so far prevented.

He also said he currently saw no partner for negotiations, and “no other option but the military solution”.

His rival, RSF leader General Mohamed Hamdan Dagalo, told Al Jazeera he was ready to implement a three-day truce over Eid.

Dagalo, widely known as Hemedti, has said several times he supported the ceasefires.

“We are talking about a humanitarian truce, we are talking about safe passages … we are not talking about sitting down with a criminal,” Dagalo said, referring to al-Burhan.

Al-Burhan accused Dagalo, until last week his deputy on the council that has ruled since a coup two years ago, of “a power grab”.

An alliance between the two men had mostly held since the overthrow four years ago of longtime strongman Omar al-Bashir.

The latest violence was triggered by disagreement about an internationally backed plan to form a new civilian government.

Both sides have accused the other of thwarting the transition.

“The two leaders’ talk about the truce is nothing more than a political tactic, and neither of them is ready for serious negotiations,” former US diplomat Timothy Carney told Al Jazeera.

“The new Sudanese state cannot have two independent armies,” he added.

Gunfire in the morning

Since hostilities erupted, much of the fighting has focused on the compound housing the army HQ and al-Burhan’s residence. The embassy district and airport have also been the scene of clashes.

Witnesses in the city of El-Obeid, east of Darfur, described clashes between the army and RSF troops and widespread looting.

In Khartoum and sister cities Omdurman and Bahri, residents gathered at bus terminals with suitcases after more explosions and gunfire in the morning.

Reporting from Khartoum late Thursday, Al Jazeera’s Haitham Uweit said “a sense of calm prevails” in the capital after a warplane was heard bombing several sites.

“Everyone is waiting to see if the two warring parties will declare a new truce because of Eid,” he said.

“A sad feeling dominates the Sudanese people, who receive Eid in this atmosphere. There are no manifestations of welcoming Eid in light of the mass flight of people of Khartoum. Usually, the Sudanese visit the neighbouring villages in a celebration of Eid, but now, they go there in sad circumstances,” he added.

In Geneva, the World Health Organisation urged the combatants to open a safe corridor for medics and to allow those trapped to flee.

Approximately 10,000 to 20,000 people escaping the fighting have taken refuge in villages along the border inside Chad, UN refugee agency UNHCR and the World Food Programme (WFP) said.