The war in Sudan has displaced nine million people internally. Another 1.7 million people have escaped Sudan to neighbouring countries.

Sudanese refugees in Chad, which has received the largest number of Sudanese, lack the most basic support necessary for survival, the NRC said, stressing that the large number of refugees has placed an unbearable strain on one of the world's poorest countries.

The NRC called for immediate and increased assistance for Chad and the broader Sudan crisis, urging world leaders to end violence in that region.

"Here in Chad, I have heard horrifying testimonies of deliberate violence and atrocities. Families fleeing neighbouring Darfur have witnessed executions, rape, indiscriminate shelling, burning of camps, and massacres -- just because of their ethnicity," said Jan Egeland, secretary-general of the NRC, upon visiting camps and Adré informal settlement in eastern Chad this week.

"Many survivors have been utterly abandoned. They are forced to live in desperate, undignified conditions, under make-shift tents, lacking even basic assistance. How is it that these survivors have been so forgotten?" he added.

More people have fled to Chad from Sudan in the last 10 months than during the entire Darfur war in 2003, according to the NRC.

Until 29 January, 682,136 Sudanese had fled to Chad, according to the International Organization of Migration.

 In Adré, the city closest to the Darfur border, 150,000 refugees are living in a self-constructed informal settlement.

Refugees outnumber locals by more than two to one in Adré, according to the NRC.

Chad ranks at the bottom of the most human development indicators and has one of the highest levels of hunger in the world. In Chad, 42 percent of the population live below the poverty line, according to the World Food Programme. In eastern Chad, host communities and refugees face nearly the same level of vulnerability.