Khartoum - Sudan wants to settle all its differences with South Sudan through talks, but sees little hope of a swift resolution while it believes Juba is backing rebels that threaten its territorial integrity, a senior ruling party official said on Sunday.
The African neighbours came close to a war when border fighting escalated in April, the worst violence since South Sudan split off and declared its independence a year ago under a 2005 agreement that ended decades of civil war.
The two have recently been trying to reconcile their many differences via talks, but Ibrahim Ghandour, a senior official in President Omar al-Hassan Bashir's National Congress Party (NCP), said it was hard to envisage progress without first resolving border security issues.
"We cannot cooperate on the economy, politics, oil, whatever, when the other party is endangering our security," Ghandour told Reuters in an interview. "We cannot build trust when the other party is supporting rebel movements with weapons and sometimes with personnel."
The duo's messy divorce left a long list of unresolved conflicts including disagreements over fees for South Sudan's oil exports and the demarcation of their shared border, as well as lingering suspicions on both sides that the other country is supporting rebel opponents.
Khartoum accuses Juba of supporting insurgencies in two of its southern border states and the western region of Darfur, the scene of a near-decade-long rebellion. Juba denies this, but some diplomats find the claim credible.
South Sudan itself often accuses Sudan of bombing its territory and said on Saturday it had suspended direct talks after another attack. Khartoum denied the bombing.
Late on Saturday, the African Union said it had managed to bring the foes back to the negotiating table.
A meeting between Sudanese President Bashir and his southern counterpart Salva Kiir that took place a week ago on the sidelines of an African Summit was billed by diplomats as a chance to inject new life into stalled bilateral talks.
But though Ghandour said it was a useful trust-building exercise, he said there had been no breakthrough.
Sudan wanted to build "very strong" cooperation with South Sudan, he added, but he questioned whether Juba was interested in a lasting settlement.
"Our history of talking to the other party will make us very cautious in being so optimistic because whenever we feel we are close to striking a deal the other party breaches whatever we had agreed upon," said Ghandour, a member of NCP's leadership team.
UN deadline looming
Talks sponsored by the African Union in Addis Ababa over where to agree a demilitarised buffer zone - seen as a first step to ending hostilities - have broken down several times.
The two countries also remain wide apart over how much landlocked South Sudan should pay to export its oil through Sudanese pipelines.
In January, Juba shut off its entire output after Khartoum started taking oil for what it called unpaid export fees. Both economies badly need the oil.
The two face the threat of sanctions from the UN Security Council unless they resolve all disputes before Aug 2. The Council has already expressed concern over delays in the talks.
Ghandour said South Sudan seemed to hope that friendly Western powers would pressure Sudan - a country isolated since the International Criminal Court indicted Bashir for war crimes in Darfur - into a deal on its terms.
"You know what they (South Sudan) are counting on is that we come to August 2 ... then it will be taken to international arbitration where their friends can take decisions in their interest," Ghandour said.
"This is their main aim. This is why they will be dragging their feet to August 2 but I don't think this is a very smart idea," he said.
Some two million people died in the conflict between the mainly Muslim north and the South, where most people subscribe to Christian or African animist beliefs. The war - fought over ideology, ethnicity, religion and oil - lasted for all but a few years between 1955 and 2005.