File: Sudanese Refugees wait for food distribution at a Maban Camp - June 2013. Photo: Joakino Francis/EyeRadio.

The UN Humanitarian Chief says rebels fighting Sudanese government forces are holding up relief and medical supplies into areas they control.

Valerie Amos told reporters that a Sudanese rebel coalition is ready to accept a ceasefire in the two-year-old conflict in South Kordofan and Blue Nile states so help can reach civilians.

The UN and western countries have said fighting between the Sudan People’s Liberation Movement-North and the Sudanese army triggered a major health and food crisis in Kordofan and Blue Nile.

The UN estimates one million people are affected by the conflict and more than 200,000 have fled to neighboring South Sudan and Ethiopia.

She also said that 150,000 children need vaccination.

The UN wants to bring medicine and food from Sudan into rebel-controlled areas.

Amos said the Sudanese government was ready to consider the operation, which it has blocked for several months, but the SPLM-North would not agree unless supplies came “across border” from South Sudan.

She said the Sudan Revolutionary Front, a coalition of anti-government groups in Sudan, had communicated in the past week and “indicated its willingness to work with UN and the African Union to reach civilians with a temporary cessation of hostilities.

Khartoum accuses South Sudan of backing the SPLM-N, a charge Juba denies.