South Sudan’s troops have pulled out of Sudan’s oil-producing Heglig area, both sides said on Wednesday, easing tensions after two days of clashes between the neighbours threatened to escalate a simmering conflict.Both the United States and United Nations called on the countries to halt the violence - the worst seen since South Sudan declared independence from Sudan in July, taking most of the country’s known crude reserves with it.South Sudan accused Sudan of bombing major oil fields and other areas on its side of the border on Monday and Tuesday. Sudan denied the air raids but said southern troops started the fighting by attacking Heglig, one of the major oilfields left on the Sudanese side of the border since the split.The United Nations said on Wednesday that the government of South Sudan had committed to withdraw its forces to its previous positions and the government of Sudan agreed to stop bombing if the South Sudan People’s Liberation Army withdrew."The Secretary-General (Ban Ki-moon) has expressed his deep concern about these military clashes and urged the parties to utilize to the fullest extent existing political and security mechanisms to peacefully address their differences,” Ban’s office said in a statement.Both governments were due to meet in Addis Ababa on March 30, the United Nations said.