JUBA/KHARTOUM: Sudan accused its old civil war foe South Sudan of aiding rebels in an attack on an oil-producing border area on Wednesday, about two weeks before the two presidents are expected to meet to try to resolve rows over oil and other issues.
South Sudan's army and the northern rebel Sudan People's Liberation Army North (SPLA-N) denied the charge, saying it was calculated to raise pressure on Juba before the talks.
South Sudan has been at loggerheads with Sudan since seceding in July under a 2005 peace deal that ended decades of civil war.
The two have yet to resolve sensitive issues such as demarcating the border, dividing debt and deciding how much the landlocked new nation should pay to export oil - the lifeblood of both economies - through Sudan.
The oil question took on new urgency when South Sudan shut down its fields in January in protest after Khartoum started taking some crude to make up for what it called unpaid fees.
South Sudan has invited Sudanese President Omar al-Bashir to meet his southern counterpart Salva Kiir in Juba on April 3 to try to resolve the dispute, complicated by fighting between rebels and government forces in border areas.
Rebels of the SPLA-N, a division of the southern army during the civil war, have taken up arms in Sudan's South Kordofan state. South Sudan's national army is still called the SPLA, but Juba denies supporting the insurgents.
Sudan's army and security forces "confronted an attack on Heglig town in South Kordofan carried out by the rebel movements which took the territory of South Sudan as a starting point," the Sudanese Media Center, a news agency linked to the state security apparatus, quoted the intelligence chief as saying.
"Half the force that executed the attack belonged to the SPLA of South Sudan," the report said.
A spokesman for the SPLA-N, Arnu Lodi, said he had not heard of any attack on Heglig. "I think this is part of a media campaign that lacks any basis in truth," he said.
"The point of this kind of talk is to win the support of citizens in Sudan in an attempt to pressure South Sudan's government during the negotiations."
Heglig is a major oil producing area under the control of Sudan, though parts of the territory are disputed.
South Sudan's armed forces spokesman Philip Aguer also said the accusation was false. "It is Sudan who has been moving forces, they are coming out of their bases," he said.
"We have been expecting an attack on Jau for the last three days," he added. "Maybe they attacked our forces and wanted to cover up. Tomorrow we will know what is happening."
Bashir's expected visit to South Sudan's capital would be his first since the African nation became independent.
The two leaders are expected to sign final agreements on two deals brokered by the African Union that ensure the free movement of citizens in one another's territory. Sudan had threatened to treat southerners as foreigners from April.
South Sudan also hopes there will be progress with oil issues at the summit, said Anne Itto, deputy secretary-general of the ruling Sudan People's Liberation Movement (SPLM).
She said Juba was offering to pay Khartoum $2.6 billion plus transit fees and a pipeline grant as compensation for allowing oil exports through Sudan. "I believe he (Bashir) would be interested in coming because I think nobody in the world wants to fight all the time," Itto told reporters in Juba.
"We are willing to do a number of things. I think this is a very great opportunity. What I cannot say is whether Khartoum will be reasonable enough," she said.
Juba will not sign an oil deal at any price and still rejects Sudan's proposal of transit fees totalling $36 a barrel, she added. South Sudan has offered to pay around $1 a barrel.
The African Union hopes the agreements on citizenship will pave the way for an oil deal.
Sudan's cabinet has warned southerners living in the north that they will have to get residency or work permits by April 8 or risk being treated as foreigners.
More than 350,000 southerners have moved to South Sudan since October 2010 after decades living in the north, but some 700,000 southerners remain in Sudan, the United Nations says.