KHARTOUM - South Sudan on Saturday said it had repulsed an attempt by the Sudanese army to retake the disputed oil-producing border area of Heglig, which the southern army seized earlier this week.Fighting between Sudan and South Sudan this week has brought the two closer to a resumption of full-blown conflict, nine months after the south seceded under a peace deal that ended decades of civil war.South Sudan seized the Heglig oilfield near the border on Tuesday, prompting widespread condemnation. The African Union denounced the occupation as illegal and urged the two sides to avert a "disastrous" war.The Sudanese army said late on Friday its forces were advancing on Heglig town, an area vital to Sudan's economy because it has a field accounting for about half of its 115,000 barrel a day oil output. The fighting has stopped crude production there, officials say."They tried to attack our positions around 40 miles north of Heglig last night but it was contained," South Sudanese Information Minister Barnaba Marial Benjamin told Reuters. "Heglig is (still) under our control," he said.Sudanese army spokesman al-Sawarmi Khalid did not answer his mobile phone when Reuters called on Saturday.South Sudan has said it will withdraw from Heglig only if the United Nations deploys forces to monitor a ceasefire.Much of the 1,800 km border is disputed between the neighbors, which are also in dispute over payments for southern oil passing through Sudan, the lifeline of both economies.Landlocked South Sudan took three quarters of the former Sudan's oil production when it seceded, but shut down in January its entire output of 350,000 barrels a day after failing to agree how much it should pay to export its crude through Sudan.The south seceded from Sudan last year but the two sides have not resolved issues including the position of the border, the division of the national debt and the status of citizens in each other's territory.Some 2 million people died in the civil war, fought for decades over ideology, religion, ethnicity and oil.