Sudan's army said it was advancing to the outskirts of a disputed town to oust South Sudanese forces from an oil-producing area.<br/> <br />South Sudan had occupied the oil fields of Heglig near the border on Tuesday, in a move that was denounced by neighbouring countries.<br/> <br />Pumping out 115,000 barrels a day, Heglig is vital to Sudan's oil production.<br/> <br />Sudan vowed to strike if the South's army did not withdraw. The South said it would only stand down if the UN intervened.<br/> <br />(SOUNDBITE) (Arabic) SUDAN'S ARMY SPOKESPERSON, AL-SUWARMI KHALID SAYING:<br/> <br />"The armed forces are continuously advancing toward Heglig and we confirm that we are now at its borders."<br/> <br />Al-Suwarmi could not verify whether the oil fields had been destroyed.<br/> <br />Recent clashes between Sudan and South Sudan have raised fears of a full-blown conflict, less than a year after the South had formed its own state.<br/> <br />The international community is calling for a stop to the fighting.<br/> <br />But disagreements over oil payments, border positions, how to divide the national debt, and the status of citizens' in each other's territory are not bringing the two sides any closer.<br/> <br />Michaela Cabrera, Reuters.