South Sudan President Salva Kiir spoke to parliament in the midst of escalating clashes along the border with Sudan. He said the country's military would also re-enter another disputed area, Abyei, currently occupied by Sudan if the United Nations does not urge Sudan to withdraw.
In New York, Sudan's U.N. Ambassador Daffa-Alla Elhag Ali Osman said if South Sudan did not withdraw, Sudan would "chase them out, and not only that, we would hit deep inside the South."
"I assure you, this occupation will not last for long," Ali Osman said.
The U.N. Security Council met in public Thursday to read out a statement demanding "a complete, immediate and unconditional end to all fighting" between Sudan and South Sudan.
The council statement, read out by presiding U.S. Ambassador Susan Rice, insisted that both countries redeploy their forces 10 kilometers (16 miles) away from a border that they both recognized last year.
Troops from South Sudan on Wednesday captured the oil-rich border town of Heglig that is claimed by Sudan, whose troops withdrew under the onslaught. Kiir said that South Sudan's military forces, the SPLA, had also advanced past Heglig after occupying it.
"They pursued them up to the so-called Heglig. But these forces did not stop in Heglig, there was not fighting in Heglig," he said.
Heglig has been the focal point of more than two weeks of clashes between the two nations. Both sides claim the area, but Sudan operates Heglig's oil facilities, which account for nearly half of the country's daily production. The town is 100 kilometers (60 miles) east of the disputed region of Abyei, whose fate was left unresolved when South Sudan split last year from Sudan.
The U.N. Security Council demanded the withdrawal of South Sudan's military forces from Heglig and an end to aerial bombing by Sudan of South Sudan. It also urged Sudanese President Omar al-Bashir and Kiir to hold a summit to resolve their conflicts.
Fighting along the north-south border has been near constant over the past two weeks. On Thursday, South Sudan accused Sudan of bombing the capital of Unity State, Bentiu.
SPLA spokesman Col. Philip Aguer said that Antonov aircraft belonging to Sudan dropped five bombs on a bridge linking Bentiu to neighboring Rubkotna. The two towns comprise Unity State's most populated area.
"This is an indiscriminate bombing," and according to initial reports one civilian was killed and four were wounded in the attack, Aguer said.
Ali Osman, the Sudanese ambassador, said any report of Sudan bombing "is just fiction."
President Kiir said he had received numerous appeals from the international community to withdraw SPLA troops from the disputed territory, including a call from United Nation's Secretary-General Ban-Ki Moon.
"Last night I never slept because of the telephone calls," he said. "Those who have been calling me—starting with the U.N. secretary-general yesterday—he gave me an order that I'm ordering you to immediately withdraw from Heglig. I said I'm not under your command," Kiir said.
The military advance by South Sudan into territory it claims but which is internationally recognized as Sudan's brought swift condemnation from the United States and Britain. Both nations, along with the U.N. Security Council, urged South Sudan to withdraw from the town of Heglig and condemned the bombings of South Sudan territory by Sudan.
Kiir said he also urged the U.N. secretary-general to re-engage Sudan on the disputed territory of Abyei.
"We withdrew from Abyei. Bashir occupied Abyei and is still there up to today," Kiir said. "I told the secretary-general that if you are not moving out with this force of Bashir, we are going to reconsider our position and we are going back to Abyei."
Late Thursday, South Sudan's U.N. ambassador, Agnes Oswaha, told reporters that there will be no withdrawal from Heglig unless and until some sort of mediation of the various disputes with Sudan is in place, and a neutral peacekeeping force is deployed in the area.
Fighting erupted in Abyei between Sudan and South Sudan May of last year, just months before South Sudan formally declared independence from Sudan.
The region was to hold a referendum in January to decide whether it stays with Sudan or joins a newly independent South. But the vote was postponed indefinitely amid disagreements over who would be eligible to vote.
The fighting has displaced more than 100,000 people, most of whom are still waiting to return.
The continued clashes have dimmed hopes for a resolution between the two countries on a host of issues left over from their July split, including oil-sharing, citizenship issues and the demarcation of the border.
Associated Press writer Peter James Spielmann contributed to this story from the United Nations.