An oil pipeline has been attacked, apparently by Sudanese fighter jets, in the latest outbreak of violence on the volatile border between Sudan and South Sudan.
Al Jazeera's Nazanine Moshiri witnessed Wednesday's air raids that took place near the town of Heglig, in a contested oil-rich area that saw heavy fighting during the Sudanese civil war.
"We were interviewing the South Sudanese minister of oil who is here assessing the situation and we actually came under attack by what looked like MiG's [fighters jets] belonging to the Khartoum government and also Antonov planes high above," she said. "We were forced to run into trenches."
There were no reports of casualties or damage after the raids, our correspondent said.
South Sudanese forces responded with anti-aircraft fire, prompting claims that one of the fighter jets had been shot down, Moshiri said.
Speaking to Al Jazeera, Barnaba Marial Benjamin, South Sudan's information minister, confirmed the air raids and said the fighter, including the pilot, was "burnt beyond recognition".
"Today at 3:00pm South Sudan local time, a MiG-29 fighter was on a bombing raid in the area. And the SPLA defence unit was able to shoot it down," Benjamin said.
"So there is concrete evidence of what we have been saying: that we are under continuous attack from the Republic of Sudan, both by air as well as from the ground."
Colonel Khaled Saad Alsawarmi, a spokesman of the Sudanese army, denied Sudan's involvement in the attack.
"Reports of the warplane shot down are a fabricated lie. No fighting took place today, and even when there were battles previously, the Sudanese army doesn't use planes, just artillery and that is after the South Sudanese army attacks first."
Baroness Valerie Amos, undersecretary general for humanitarian affairs at the UN, told Al Jazeera that they have witnessed thousands of people fleeing across the border into South Sudan.
"We all want the fighting to stop and for the leaders to sit down and talk this out," she said. "A lot of people are talking about [an impending war]/ We are all boping it will not get to that.... from my perspective, we've been focusing on the people who need help."
She went on to say with the drought crisis continuing, the area "is facing a potential food crisis," which needs to be dealt with immediately.
Former South African president Thabo Mbeki arrived in Juba, South Sudan's capital, on Thursday for talks with the country's leader, Salva Kiir.
Heglig is situated within the Muglad Basin, a rift basin which contains much of Sudan's proven oil reserves.
During Sudan's civil war, the South Sudanese People's Liberation Army (SPLA) rebels attacked the oil rigs of Heglig to limit the oil revenue for the Sudanese government.
Tension has been growing in the area in recent weeks, as South Sudan, which gained independence last year, and Sudan continue their dispute over oil fields and control of other areas.
"What we see on the ground here seems to confirm the escalation of tensions and clashes, which is deeply worrying to the international community that is trying to get the two sides to talk in Addis Ababa," Moshiri said.
Sudan and South Sudan failed on Wednesday to sign an agreement in the Ethiopian capital to resolve the disputes that sparked the recent eruption of violence in the contested border region.
South Sudan accused Khartoum's delegation of walking out of the latest round of African Union-led crisis talks, but a Sudanese minister voiced confidence that a deal will be signed when negotiations resume next week.
The UN Security Council expressed alarm on Tuesday at recent clashes between Sudan and South Sudan along their disputed border and urged both sides to halt military operations, warning the fighting could escalate into a new war.
"The Security Council call upon the governments of Sudan and South Sudan to exercise maximum restraint and sustain purposeful dialogue in order to address peacefully the issues that are fueling the mistrust between the two countries," the 15-nation council said in a statement.