UN Secretary-General António Guterres said on Wednesday that the UN is working closely with the African Union and the Inter governmental Authority on Development (IGAD) on ending the conflict in Sudan.

Fighting broke out on April 15 between Sudan’s de facto leader Abdel Fattah al-Burhan, who commands the regular army, and his deputy turned rival Mohamed Hamdan Dagalo, who heads the paramilitary Rapid Support Forces (RSF).

“All parties must put the interests of the Sudanese people first, and that means peace returns to civilian rule allowing for the development of the country. We are putting these goals front and centre as we engage with the parties of the conflict and work with hand in hand with the African Union, and Inter Governmental Authority on Development (IGAD)”, said António Guterres, UN Secretary-General.

The conflict in Sudan has sparked a massive exodus of more than 100 thousand refugees that have fled to neighbouring countries.

“It is absolutely essential to massively support Chad in the present situation. On the other hand, we have other countries in the region that are in their own peace processes. Ethiopia is in a peace process. It is absolutely essential to avoid any spill-over from Sudan to Ethiopia”, alerted the UN official.

Speaking during a press conference held in Nairobi, Guterres admitted that “the UN was taken by surprise” by the conflict, adding “to the extent that we and many others were not expecting this to happen, we can say we failed to avoid it to happen”.

The fighting in Sudan has killed at least 550 people. The warring sides have announced multiple truces but none has effectively taken hold.

The UN’s humanitarian chief arrived at Sudan’s main seaport on Wednesday, as thousands of Sudanese and foreign nationals gathered there in hopes of fleeing by plane or boat.

The battle for control of Sudan erupted after months of escalating tensions between the military, led by Gen Abdel-Fattah Burhan, and a rival paramilitary group called the Rapid Support Forces, commanded by Gen Mohamed Hamdan Dagalo.

On Wednesday Martin Griffiths, the under-secretary-general for humanitarian affairs and emergency relief coordinator at the United Nations, tweeted that he had spoken with both leaders.

His arrival in the Red Sea port came on the last day of a shaky truce, meant to expire at midnight, that has done little to quell the fighting.

It also comes amid increasing concern about the humanitarian situation for those trapped and displaced by the fighting, which is the result of a power struggle between the country’s two top generals. But questions remain over how U.N. agencies can operate with limited staff and supplies amid the chaos. More than a week after the brutal fighting erupted in the country’s capital on Khartoum on April 15, thousands of U.N. workers were evacuated from the city by way of a land convoy to Port Sudan. Some U.N. offices paused their services, such as the World Food Programme, after two of its workers were killed in fighting in southern Sudan. The WFP has since said it will resume operations.