JUBA  - South Sudan accused Sudan of launching air strikes on the southern side of their disputed border shortly before the leaders of the oil-producing African countries were due to meet to defuse tensions. Sudan’s armed forces were not immediately available for comment but have regularly denied southern accusations of attacks in the past. The two countries have been at loggerheads over oil, territory and a string of other disputes since the South split away from Sudan last year. They came close to war in April and have yet to withdraw their armies from their shared boundary or resume oil exports from the landlocked South through Sudanese pipelines.