Thousands of Sudanese flock to Chad as UN calls for access to western Sudan to deliver much-needed aid amid humanitarian crisis.

“Darfur is an area we have not been able to access and there is significant fighting [there],” Clementine Nkweta-Salami, the UN’s humanitarian coordinator for Sudan, told Al Jazeera on Saturday.

“We need to be able to bring in staff. We need to be able to get agreements so that we can move along the routes [and] our trucks that are presently in parts of the country can make their way to Darfur,” she said, calling for a security agreement for the safe movement of aid.

In the two months since the Darfur city of el-Geneina has been under siege, Adam Mohd Yousef has lost 22 members of his family – 15 of them children.

“The Sudanese government didn’t help us. They see what is happening and just watch us burn,” he told Al Jazeera, bursting into tears.

Yousef is among the thousands of Sudanese refugees crossing into Chad to escape violence in the continuing war between Sudan’s army and the paramilitary Rapid Support Forces (RSF), with the situation in Darfur particularly catastrophic according to humanitarian groups and international actors.

“The UNHCR is here assessing the situation and they say it has never – in the past two months of war – ever, been this bad, certainly not at this border check post in Adre,” said Al Jazeera’s Zein Basravi, from the Chadian city on the border with Sudan.

The UNCHR says there is not enough international interest in the crisis and that they are underfunded, Basravi said.

At least 1,000 people have been killed in el-Geneina in particular, where there have been new waves of attacks by Arab nomadic tribes with ties to the RSF. The fighting has also sent more than 270,000 refugees across the border to Chad.

The refugees at the Adre checkpoint told Al Jazeera their city of el-Geneina no longer exists, as thousands turn up each day to the border crossing, tired, desperate, and in fear for their lives and future. Many of those crossing are also unaccompanied children who are picked up by strangers along the way.

“I don’t know where my children are. I had to leave them behind,” a sobbing woman told Al Jazeera, before falling down in exhaustion.

While UN agencies like the World Food Programme (WFP) have been able to get aid in other fighting strongholds like the capital, Khartoum, they have been unable to provide relief in Darfur.

On Thursday, the United States and UN said the situation there could herald a repeat of past mass atrocities.

Events in the region are “an ominous reminder of the horrific events that led the United States to determine in 2004 that genocide had been committed in Darfur,” the US State Department said in a statement.

“Darfur is rapidly spiraling into a humanitarian calamity. The world cannot allow this to happen. Not again,” UN aid chief Martin Griffiths also said in a statement.

On Wednesday, the killing of West Darfur state Governor Khamis Abakar after he publicly blamed the deaths of civilians on the RSF marked a new escalation in the conflict.