JUBA/KHARTOUM South Sudan said on Saturday the Sudanese army had bombed its positions in the oil-producing border area, resuming a conflict that had eased earlier this week, just hours ahead of new talks.
Trading accusations, Khartoum said South Sudan had supported a rebel attack on a border town in South Kordofan state and was building up troops at the poorly-marked frontier where fighting flared on Monday and Tuesday.
Those skirmishes ended when southern troops moved out of the disputed Heglig oil field, on the Sudan side of the border, where they had gone in response to what they said was Khartoum's bombing of southern oil fields.
It was the worst direct confrontation between the neighbors since South Sudan became independent in July under a 2005 agreement that ended decades of civil war.
Both sides are to resume talks in Addis Ababa on Saturday but diplomats see no breakthrough after Sudan's President Omar Hassan al-Bashir called off a summit with his southern counterpart Salva Kiir due to the violence.
Philip Aguer, spokesman for South Sudan's army, the SPLA, said on Saturday the Sudanese army had bombed SPLA border positions.
"They have been bombing our positions since yesterday at 5 p.m. Their target seems to be to invade Unity (state) oil fields. They are the ones bombing our forces in different places and pushing southwards," he said.
South Sudan's Information Minister Barnaba Marial Benjamin said the clashes were "minor" and did not amount to an escalation.
Sudanese army spokesman Sawarmi Khaled Saad accused the SPLA of helping rebels of the SPLM-North conducting an assault on the border town of Talodi in South Kordofan.
"South Sudan supported the rebels with tanks and artillery," he told state news agency SUNA late on Friday, adding that rebels had failed to take the town and had fled to regroup.
He also said the SPLA army was amassing troops at the border south of Heglig. "The goal is to attack the Heglig area another time," Saad said.
Aguer denied the SPLA had supported the rebel attack.
The Heglig field is key to Sudan's economy because it produces around half of the country's oil output of 115,000 barrels a day.
The field was awarded to Sudan by the Permanent Arbitration Court in 2009 but some southern officials have laid claim on it.
The border states of South Kordofan and Blue Nile are home to populations which sided with the south during the civil war but were left on the Sudan side of the border. The Sudanese army has been fighting SPLM-North in both states since last year.
(Writing by Uf Laessing; Additional reporting by Khaled Abdelaziz; Editing by Robin Pomeroy)