Sudanese aircraft have renewed bombings across the border in South Sudan, hitting targets across Unity State and leaving one person dead and three others wounded, a military official has said.
Major General Mac Paul, the deputy director of military intelligence for South Sudan, said on Monday that two MiG 29 fighter planes dropped three bombs, two of which landed near a bridge that connected Bentiu, the capital of Unity State and Rubkona.
"This is a serious escalation and violation of the territory of South Sudan. It's a clear provocation," Paul said.
Paul said ground troops from Sudan launched three waves of attacks about 10km on its side of the border.
"We are building up troops because we think that the Sudanese army is also building up," he said.
Khartoum has denied the accusations, but said it had repelled a "major" attack by SPLM-N fighters in South Kordofan state, on its own side of the border. Sudan routinely says the fighters are controlled by the South, an accusation Juba denies.
"We have nothing to do with what is going on in Unity State," Sudan's army spokesperson said.
Amid the escalating tension between the archfoes, Omar al-Bashir, the Sudanese president, has arrived in the oil-rich town of Heglig.
It is Sudanese president’s first visit to this oil-rich border region after it claimed to have liberated from Southern forces last week. He landed at about 0950 GMT, dressed in a military uniform.
The United Nations Mission in South Sudan (UNMISS) has deplored the bombings.
"These indiscriminate bombings resulting in the loss of civilian lives must stop," Hilde F Johnson, Special Representative of the Secretary-General for South Sudan, said.
Al Jazeera’s Peter Greste, reporting from Bentiu, said: "High flying aircraft dropped bombs mostly around a military base north of Bentiu."
"There was firing from the South Sudanese ground troops to bring the aircraft down. A lot of Southern troops are advancing towards the frontline as enforcement," he said.
"It is difficult to know what Sudan’s overall strategic objective really is here.
"Sudan’s President has said [he wants] to bring the southern government down - that might well be what they are planning to do."
Sudan and South Sudan have been drawing closer to a full-scale war in recent months over the unresolved issues of sharing oil revenues and the disputed border.
The international community, led by the US, has called for the two countries to stop all military action against each other and restart negotiations to solve their disputes.
On Friday, Barack Obama, the US president, asked the presidents of Sudan and South Sudan to resume negotiations and said that conflict was not inevitable.
Talks between the two countries over the unresolved disputes, that were being mediated by the African Union (AU), broke down in Ethiopia earlier this month.
The AU on Sunday called on Sudan and South Sudan to end "senseless fighting".
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"The commission urges the two parties to immediately and unconditionally resume negotiations ... to reach agreements on all outstanding issues,'' Jean Ping, AU Commission Chairman, said in a statement.
A US monitoring group said on Sunday that satellite imagery appeared to show the fighting around Heglig had caused major damage to oil pipeline infrastructure.
The Satellite Sentinel Project said the images showed severe damage, and in such a critical part of the oil infrastructure that it would probably stop oil flow in the area.
Sudan's official news agency, SUNA, said late on Sunday the Sudanese ministry of petroleum and oil companies operating in the Heglig oilfield had started repairing the oil installations which had been damaged by South Sudan's army
during their invasion of Heglig region.
South Sudan broke away from Sudan in July last year after an independence vote, the culmination of a 2005 peace treaty that ended decades of war that killed more than two million people.
Source: Al Jazeera and agencies