The first UN food aid has been allowed into Sudan's war-torn Blue Nile state in a "major breakthrough," the World Food Programme said on Thursday, after severe government restrictions.
"This is the first time that the agency has distributed food assistance since the conflict broke out in September 2011," the WFP said.
The war in Blue Nile and South Kordofan has raged largely out of world view as Sudan, citing security concerns, tightly constrained the movement of foreign aid workers, diplomats and reporters seeking to visit the region.
"While we continue to strive for access to all areas, this is still a major breakthrough which will enable us to assist those who continue to be displaced by the conflict or those who have decided to return to their homes and are in dire need of food assistance," WFP Sudan director Adnan Khan said in a statement.
In South Kordofan, authorities had already allowed WFP to distribute food in a limited area, but rebel zones in both states remain off limits.
Allowing WFP to begin work in Blue Nile is the latest sign of an easing of tensions since Sudan and South Sudan finally settled on detailed timetables in early March to implement crucial economic and security pacts.
Khartoum had accused the South Sudanese government of backing rebels of the Sudan People's Liberation Movement-North (SPLM-N) in Blue Nile and South Kordofan.
More than 200,000 people have fled the war-affected states to South Sudan and Ethiopia as refugees, the UN says.
An estimated one million more have been affected inside South Kordofan and Blue Nile, where a senior UN aid official has said people were surviving on "roots and leaves".
The WFP has begun distributing rations of sorghum, lentils and salt in Geissan district, on the Ethiopian border, and says it expects to soon move into the Kurmuk area.
The agency plans to reach about 12,000 people in Geissan and another 39,000 in Kurmuk. Most of them are displaced, said Amor Almagro, of the WFP's Khartoum office.
The aid distribution comes after the WFP was allowed to assess the needs of people in the two districts early last month.
"They collected grass and palm leaves, and some charcoal, and they sold that" in order to survive, Almagro said the assessment revealed.
But people also reported that they had received food from the government, she added.
Sources told AFP in February that there had been fighting in Kurmuk, the third-largest town in Blue Nile.