South Sudan's President Salva Kiir with China's President Hu Jintao

South Sudan\'s President Salva Kiir with China\'s President Hu Jintao Khartoum – Agencies Khartoum has declared war on South Sudan, according to the South\'s leader. His comments came as the violence between the two countries intensified and the UN called for an end to fighting .
South Sudan President Salva Kiir said Tuesday that Sudan had declared war on his country. He made the comments during a visit to China to boost ties between Juba and Beijing.
Kiir told his Chinese counterpart, Hu Jintao, that his trip came at \"a very critical moment for the Republic of South Sudan, because our neighbour in Khartoum has declared war on the Republic of South Sudan.\"
In New York, the UN Security Council was briefed on the situation late on Tuesday. The 15-nation body was told that aerial bombardment of South Sudan’s  Unity State on Monday night had killed 16 civilians. Members demanded “an immediate halt to aerial bombardments by the Sudanese armed forces and urged an immediate cease-fire and return to the negotiating table,” US ambassador to the UN and current council president Susan Rice told reporters.
The fighting erupted after South Sudan\'s military seized the Heglig oil field two weeks ago. South Sudan said on Sunday it had withdrawn its forces from the oil town.
Nine months after the separation of South Sudan from the north, the two sides are now involved in daily border skirmish. Hours earlier, Sudanese warplanes had bombed border areas in South Sudan. Eight bombs hit the area of Pankuac, South Sudan\'s military spokesman Col. Philip Aguer told the Associated Press.
In New York, the UN Security Council was briefed on the situation late on Tuesday. The 15-nation body was told that aerial bombardment of South Sudan’s s Unity State on Monday night had killed 16 civilians.
Members demanded “an immediate halt to aerial bombardments by the Sudanese armed forces and urged an immediate cease-fire and return to the negotiating table,” US ambassador to the UN and current council president Susan Rice told reporters.
The fighting erupted after South Sudan\'s military seized the Heglig oil field two weeks ago. South Sudan said on Sunday it had withdrawn its forces from the oil town.
China\'s Hu called on the two countries to resolve the conflict through negotiation, repeating similar statements made by China\'s foreign ministry.
\"The top priority is to actively cooperate with the mediation efforts of the international community to stop the armed conflict in the border region,\" Hu was quoted as saying by Chinese state television.
Neither Sudan nor South Sudan has so far issued a formal declaration of war.
Bashir has threatened to crush the \"insect\" government of South Sudan and vowed to continue his military campaign until all southern troops were pushed out of the north.
The two countries have been unable to resolve disputes over borders and oil revenues since South Sudan seceded from Khartoum in July after gaining independence in a referendum.
While South Sudan\'s president has accused his northern neighbour of declaring war, soldiers in this region scarred by recent battles say they are simply defending their borders.
\"If we want to go to the South now we can... but that is not our plan,\" said Zaki Al Ahmad, a fast-talking member of the Popular Defence Force (PDF), at a collection of straw huts serving as their base in this oil region about 15 kilometres (nine miles) from the disputed border.
\"We are just defending our property. We don\'t want to attack them,\" said one bearded fighter, speaking four days after Sudan announced its troops were forced out by South Sudanese who had occupied the north\'s main oilfield of Heglig for 10 days.
The South, however, said its troops withdrew in a process that ended on Sunday.
\"Welcome to liberated Heglig. God bless the martyrs who spilled their blood,\" announced a crewman aboard an aircraft flying in journalists on a four-hour government run trip to the region which is normally off-limits to reporters.
A village near the airport has been almost completely burned to the ground.
\"Now our forces are settled on the borders of 1956,\" said Mohammed Khalil, 23, describing himself as a \"mujahid\" who volunteered for the PDF, a mainstay of Sudan\'s fighting corpse.
Sudan has demanded that the South recognise the borders which existed at Sudan\'s independence from Britain and Egypt on January 1, 1956.
Khalil, who normally works as an engineer in the capital Khartoum, said troops will stay in Heglig \"until we feel safe and our borders are safe.\"
Over the frontier in South Sudan\'s Unity state, Sudanese warplanes left several people wounded from air strikes that continued into the early hours of Tuesday, the state\'s governor Taban Deng said.
United States Secretary of State Hillary Clinton denounced the air raids as \"provocative and unacceptable\",
A senior officer in the South Sudan army alleged Sudan was mobilising for a push on the city of Bentiu, more than 100 kilometres (60 miles) from Heglig.
\"We don\'t like war,\" the Sudanese armed forces commander, Kamal Marouf, said in Heglig.
A manager at the damaged main oil facility, Ibrahim Yousif Gamil, said there were actually fewer troops now than in recent days.
\"The presence of the army is to the minimum now,\" he said.
Still, soldiers are about the only people visible in this flat region dotted with acacia trees.
Pickup trucks with troops standing behind machine guns speed along the main road, throwing up clouds of red dust that sting the eyes.
Troops have set up crude camps, and more than 100 green crates of military equipment are stacked beside one building.
PDF pickup trucks are crammed with ammunition, rifles, shovels, and mounted rocket propelled grenade launchers.
\"Don\'t ask about the weapons,\" one fighter with a cloth tied around his head admonished an AFP reporter.
In the far distance, an explosion sounded