(CNN) -- The U.N. Security Council has called for an immediate end to the escalating conflict between Sudan and South Sudan over a disputed oil-rich border region.
The border clashes have threatened to return the neighbors to a full-scale war.
"The Security Council demands a complete, immediate and unconditional end to all fighting and a withdrawal of the SPLA from Heglig and an end to aerial bombardments," said Susan Rice, president of the Security Council and U.S. ambassador to the United Nations.
Earlier this week, South Sudan's military, the SPLA, seized Heglig, a key oil installation in South Kordofan that produces nearly half of Sudan's oil.
It follows a series of clashes in the volatile border region between the two countries, which separated when South Sudan gained independence in July.
Sudan's ambassador to the United Nations welcomed the Security Council statement calling for withdrawal.
"We will observe closely the behavior and attitude of the reaction of the government of the South to this call and if they don't heed it, we will reserve our right to exercise the right of self defense and we will chase them out, " said Daffa-Alla Elhag Ali Osman.
South Sudan's ambassador to the United Nations blamed the Khartoum government for attacks on their forces at the border, which she said provoked their actions at Heglig.
"South Sudan had no choice. It had to defend itself to deter attacks on South Sudanese territory," Agnes Oswaha said. "South Sudan is prepared to withdraw troops as long as a mechanism is put in place that the area cannot be used to launch further attacks."
Leaders of both countries weighed in Thursday.
Sudan President Omar al-Bashir said his army is poised to "repulse any aggression," but said the nation "has no interest" to return into war with its neighbor. He made the statement in Sudan's official news agency, SUNA,
His South Sudan counterpart, Salva Kiir, speaking to parliament in Juba, said he would not order his forces to withdraw from Heglig. He claimed that Bentiu town, the main center of nearby Unity State, was bombarded Thursday morning with one fatality.
The International Community has reacted with alarm to the escalating crisis in Sudan.
European Union foreign policy chief, Catherine Ashton, said South Sudan's move to occupy Heglig is "completely unacceptable" and called on forces to withdraw immediately.
The African Union, which was set to broker talks between the two sides in early April, has called for the forces to withdraw from Heglig and aerial bombardments to stop.
China also expressed concern about the tensions.
" We hope the two countries can exercise restraint and stop using violence and solve their conflicts and differences through dialogue and negotiations," said Liu Weimin, a spokesman for the Chinese ministry of Foreign Affairs.
South Sudan gained independence from the north in July, the result of a referendum overwhelmingly approved by voters last year.
The referendum was part of a 2005 peace deal that ended decades of civil war between the two that killed about 2 million people.
Despite the split, several outstanding have yet to be negotiated, including citizenship, border demarcations and oil revenue sharing.
When they separated, South Sudan acquired three quarters of Sudan's oil reserves. The two countries have been locked in negotiations over how much the landlocked South Sudan should pay to use a pipeline and processing facilities in the north.
In late July, South Sudan halted oil production after accusing Sudan of "stealing" $815 million worth of its crude. Sudan said it confiscated the oil to make up for unpaid fees.