Sudanese government forces and rebels said on Tuesday there has been fresh fighting in Blue Nile state, part of a war zone where the UN reports worsening humanitarian conditions.The Sudanese Media Centre, which is close to the security apparatus, said late Monday that troops had repelled a rebel attack against the Diem Mansour area south of Kurmuk, which is near the Ethiopian border.It quoted Sudanese army spokesman Sawarmi Khaled Saad as saying rebels had suffered heavy losses.He could not be reached for comment by AFP."SPLM has launched an attack... south of Kurmuk,” and fighting continues, said Arnu Ngutulu Lodi, spokesman for the Sudan People’s Liberation Movement-North (SPLM-N).He told AFP on Tuesday that the rebels began on Monday their effort to retake the area. He had no casualty figures.Access to Blue Nile is severely restricted, making independent verification of the claims difficult.Ethnic insurgents of the SPLM-N fought alongside southern rebels during Sudan’s 22-year civil war, which ended in a 2005 peace deal and South Sudan’s independence in July last year.Fighting began in September between the army and forces loyal to rebel leader Malik Agar, who was then the elected SPLM-N Blue Nile governor. The SPLM-N has been fighting a similar war in South Kordofan state since June last year.More than 200,000 refugees from South Kordofan and Blue Nile have crossed into South Sudan and Ethiopia, and thousands more "in a desperate state” are following each day, UN emergency relief coordinator Valerie Amos said last week.She said she was "deeply concerned by the deteriorating humanitarian situation”, and added hundreds of thousands of people remain trapped in the conflict zone with little access to food, water, shelter and medical services.Sudan accuses South Sudan of supporting the SPLM-N, a charge which foreign analysts believe despite denials by the government in Juba.The Sudanese government has accepted a plan put forward by the UN, African Union and Arab League to get aid into South Kordofan and Blue Nile.But Amos said the Khartoum government "has laid out operational conditions that do not allow for the delivery of assistance by neutral parties in SPLM-N controlled areas.”The African Union welcomed Sudan’s acceptance of the plan and urged "all those responsible to ensure that it is effectively and fully implemented without further delay”.The AU said it is ready to send personnel for joint humanitarian assessment teams, as well as monitors.Last year the SPLM-N joined insurgents from the Darfur region in a Revolutionary Front to overthrow the Khartoum regime.