South Sudan has said its soldiers have retained control of a key town in the oil-producing border region of Heglig despite clashes with Sudanese forces.
Philip Aguer, a spokesman for South Sudan's military, known as the Sudan People's Liberation Army (SPLA), said on Saturday there had been overnight clashes in Kelet, a village about 40km from Heglig town.
"Yesterday, there were clashes between their patrols and SPLA. ... SPLA has destroyed two tanks belonging to the SAF," Aguer said.
Al Jazeera's correspondent Nazanine Moshiri, reporting from Juba, said as many as five people were killed in the bombings.
"We understand the four civilians and one soldier were killed in the bombings of a strategic bridge leading to the frontlines," said Moshiri, adding that the situation does "seem to be escalating as Sudanese forces claim to marching on to Heglig".
|Al Jazeera's correspondent Nazanine Moshiri with the latest updates from Juba
But Colonel Alsawarmi Khalid Saad, a spokesperson for the Sudan military, said that the armed forces were close to Heglig and engaging South Sudanese troops a few kilometres from the oilfield.
"We are within the perimeter of the city itself ... our armed forces are engaged in sporadic military operations with those stationed from the remnants of the South Sudan army who are still positioned in Heglig.
"We can see our forces advancing and they [South Sudan army] is retreating."
Colonel Saad said that Sudan's immediate aim was not to take the town but to destroy the South's "war machine".
Aguer denied those claims, estimating that Sudanese troops were about 30km away from the main town.
Colonel Saad, meanwhile, denied claims that the Sudanese army was targeting civilians.
"These allegations are baseless and untrue. We are not targeting civilians. However, their forces are invading our state and we are engaged in an all out war within our perimeters [and] so we cannot be targeting our fellow Sudanese citizens," he said.
South Sudan's information minister said Sudanese efforts to regain Heglig had been repelled.
"They tried to attack our positions north of Heglig last night but it was contained," said Barnaba Marial Benjamin. "Heglig is [still] under our control."
South Sudanese forces seized control of Heglig town earlier in the week during the worst fighting in the region since the South seceded from Khartoum's rule last year.
|In-depth coverage of North-South strife over border
Aguer, spokesperson of the South Sudan army, confirmed that Sudan's air force bombed the border areas of Jau and Panakuach, in northern South Sudan's Unity State, on Saturday, as well as Heglig, the main producer of Khartoum's oil.
A Unity State government spokesperson, reached by telephone in the state capital Bentiu, confirmed the aerial bombings near the border.
"The areas in the north of Unity State are still subject to Antonovs [planes]," said the spokesperson, Gideon Gatfan. "We don't have the updates yet between Heglig and Kelet, but all those areas they are subjected to bombing."
Earlier on Friday, our correspondent Nazanine Moshiri, said a spokesperson there had told her Sudanese forces were about 30km from Heglig and that South Sudanese would defend themselves if they attempted to take back the town.
"This could end up becoming a full-blown conflict," our correspondent said.
World powers and the United Nations have urged restraint after the latest round of heavy fighting that broke out on Tuesday.
The African Union denounced the South's occupation of Heglig as illegal and urged the two sides to avert a "disastrous" war.
Fighting in Heglig has halted oil production amounting to about half of Sudan's 115,000 barrel-a-day output and damaged facilities, officials say.
Speaking in Nairobi, Pagan Amum, South Sudan's lead negotiator at talks to resolve the dispute with Sudan, said his country was ready to withdraw under a UN-mediated plan.
"On the ground, we are ready to withdraw from Heglig as a contested area ... provided that the United Nations deploy a UN force in these contested areas and the UN also establish a monitoring mechanism to monitor the implementation of the cessation of hostilities agreement," he told reporters.
The South seceded from Khartoum's rule last year but the two sides have not agreed on issues including the position of the border, the division of the national debt and the status of citizens in each other's territory.
Amum said there were seven disputed areas and called for international arbitration to settle the issues.
The loss of Heglig's oil output is another blow to Sudan's economy, which is already struggling with rising food prices and a currency depreciating on the black market.
"Resumption of oil in that area will only come when the UN deploy their forces between the two countries and in the disputed areas and when the two countries reach agreement to resume oil production," Amum said.
Landlocked South Sudan shut down its own 350,000 barrel-per-day oil output in January in a row over how much it should pay to export crude via pipelines and facilities in Sudan.
Oil accounted for about 98 per cent of the new nation's state revenues and officials have been scrambling for ways to make up for the loss.
In Juba, about 200 people demonstrated at a government-organised protest against Sudan and in support of the occupation of Heglig, holding banners which read: "The people want the army to be in Heglig" and "They bomb children and women".