Up to 20,000 people have fled the escalating violence in Sudan to seek safety in neighbouring Chad, many of whom lack basic needs such as food, water and shelter, the United Nations has said. The UN’s refugee agency said the majority of those arriving were women and children, who were currently sheltering out in the open, some of whom had been caught up in the fighting that has raged around the country for six days. “In the past days, an estimated 10,000 to 20,000 people have fled the conflict in Sudan’s Darfur region to seek refuge in neighbouring Chad,” the UNHCR agency said, citing figures from its teams at the border. “Due to the violence experienced by those crossing the border, psychosocial support is also among our top priorities,” the agency said. It comes as the leaders of Sudan’s rival military forces said they were unwilling to negotiate with each other. Sudan’s military ruler, Abdel Fattah al-Burhan, and Mohamed Hamdan Dagalo, known as Hemedti, who leads the paramilitary Rapid Support Forces (RSF), spoke to Al Jazeera on Thursday. “There is no other option but the military solution,” Burhan said in a phone interview, in which he also accused elements in the RSF of “closing roads and preventing the free movement of people” in many regions. “A real truce cannot be implemented in these conditions,” he added. Hemedti accused Burhan of starting the fighting and said that therefore there could be no future negotiations with him. The interviews, which cast doubt on the prospect of a lasting ceasefire, came as the UN secretary general, António Guterres, asked both sides to implement a ceasefire over the Muslim Eid al-Fitr holiday to allow civilians to reach safe areas. 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. Hemedti told Al Jazeera he was ready to implement the three-day truce over Eid, which marks the end of the Muslim holy month of Ramadan and will start on Friday or Saturday. “We are talking about a humanitarian truce, we are talking about safe passages … we are not talking about sitting down with a criminal,” Hemedti said, referring to Burhan. Hemedti has said several times he supports short ceasefires but each has quickly collapsed. Nearly 300 people have been killed and thousands more injured since the fighting erupted on Saturday. The conflict has pitted army units loyal to Burhan, the head of Sudan’s transitional governing sovereign council and the regular army, against the RSF, led by Hemedti, who is deputy head of the council. Their power struggle has derailed a shift to civilian rule and raised fears of a long, brutal civil war. Explosions and gunfire were heard across Khartoum again on Thursday and there has also been widespread violence in remote areas, particularly in the restive south-western region of Darfur. In Nyala, a city in South Darfur, RSF forces have wrested control of many former army bases and are now in control. Dozens of facilities run by international aid organisations in the region have been looted or burned, along with government offices, and many civilians killed or wounded, according to local civil society sources. One activist said: “The situation is calm at the moment but we are afraid. The terrifying thing is that the markets are all burned and they were the basic supply place for seeds, foods, everything we need to live so that is a real disaster. The roads are closed everywhere so we are totally cut off. We are at the mercy of the militia now.” In Khartoum, civilians have been trapped in schools, colleges, hospitals and their homes without electricity, food and water since the fighting began. Another truce unravelled on Wednesday evening. “We were awoken today at about 4.30am to the roaring sound of fighter jets and airstrikes,” said Nazek Abdalla, 38, in southern Khartoum. “We locked our doors and windows hoping no stray bullets would hit our building.” Around the capital and elsewhere, RSF fighters atop armoured vehicles and pickup trucks laden with weapons have taken over entire streets, sometimes setting up checkpoints to search cars carrying civilians trying to escape Khartoum’s worst battle zones to safer areas in the capital and beyond. Witnesses said RSF fighters were seen taking food from homes, as well as valuables, suggesting the force was running low on supplies. Doctors in Khartoum have reported acute shortages of medicines, fuel, clean water and power as they try to cope with a flood of wounded and sick. More than two-thirds of medical facilities in Khartoum are now out of service due to the fighting, the country’s main doctors’ union said. US officials said on Thursday that the Pentagon is moving additional troops to a base in Djibouti to prepare for the possible evacuation of embassy personnel. Other countries have also started to make plans to evacuate thousands of foreigners, but their efforts have been put on hold by the ongoing violence. Many international humanitarian staff have sought shelter at the 300-bed Rotana hotel in Khartoum, where more than 1,000 people are now staying. Burhan and Hemedti toppled the autocratic president Omar al-Bashir together in April 2019 after months of huge protests against the dictator’s three decades of repressive rule. They then marginalised political parties and terrorised pro-democracy campaigners before working together in October 2021 to overthrow the civilian government installed after Bashir’s fall, derailing an internationally backed transition to democracy.