South Sudan's president said its northern neighbor has "declared war" on the world's newest nation, just hours after Sudanese jets dropped eight bombs on his country.
President Salva Kiir's comments, made Tuesday during a trip to China, signal a rise in rhetoric between the rival nations, who spent decades at war with each other. Neither side has officially declared war.
Sudan and South Sudan have been drawing closer to a full-scale war in recent weeks over the unresolved issues of oil revenues and their disputed border. The violence has drawn alarm and condemnation from the international community, including from U.S. President Barack Obama.
South Sudan won independence from Sudan last year as part of a 2005 peace treaty that ended decades of war that killed 2 million people.
The U.N. Security Council was briefed on the situation late Tuesday and 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," Susan Rice, the U.S. ambassador to the United Nations and the current council president, told reporters at U.N. headquarters in New York.
Sudanese President Omar al-Bashir gave a fiery speech last week in which he said there will be no negotiations with the "poisonous insects" who are challenging Sudan's claim to disputed territory near the border.
Kiir, the southern president, arrived in China late Monday for a five-day visit to lobby for economic and diplomatic support. China's energy needs make it deeply vested in the future of the two Sudans. Beijing is uniquely positioned to exert influence in the conflict, given its deep trade ties to the resource-rich south and decades-long diplomatic ties with Sudan's government in the north.
Kiir told Chinese President Hu Jintao the visit comes at a "a very critical moment for the Republic of South Sudan because our neighbor in Khartoum has declared war on the Republic of South Sudan."
South Sudan's military spokesman Col. Philip Aguer said that Sudanese Antonov warplanes dropped eight bombs overnight in Panakuac, where he said there was ground fighting on Monday. Aguer said he did not know how many people were killed in the attack because of poor communication links with the remote area.
On Monday, Sudanese warplanes bombed a market and an oil field in South Sudan, killing at least two people, after Sudanese ground forces reportedly crossed into South Sudan with tanks and artillery.
The U.N. Mission in South Sudan confirmed that at least 16 civilians in South Sudan were killed and 34 injured in bombings by Sudanese aircraft in Unity State, ambassador Rice told reporters. She said the mission reported that the bombings also caused significant damage to infrastructure.
Talks over oil revenue and the border issues broke down this month after violence flared. South Sudan invaded the oil-rich border town of Heglig, which Sudan claims it controls.
Following international pressure, South Sudan announced that it withdrew all its soldiers from Heglig. Sudan claimed its troops forced them out.
Rice said the Security Council welcomed the withdrawal of South Sudan's forces from Heglig. She said many of the 15 council nations expressed concern about reports of extensive damage to oil infrastructure in Heglig.
Al-Bashir, the Sudanese president, has vowed to press ahead with his military campaign until all southern troops or affiliated forces are chased out of territory Sudan claims.
He also said he would never allow South Sudanese oil to pass through Sudan "even if they give us half the proceeds."
Landlocked South Sudan stopped pumping oil through Sudan in January, accusing the government in Khartoum of stealing hundreds of millions of dollars of oil revenue. Sudan responded by bombing the South's oil fields.
In Khartoum, the pro-government Sudanese Media Center said that two of Sudan's Darfur states began implementing a ban on shipping to South Sudan. The ban was imposed by Sudan's parliament.
Officials in the Darfur states said they warned merchants that "stern measures will be taken against any person found to be smuggling food supplies and other commodities into South Sudan," the SMC reported.
Sudanese officials said the measures were imposed in response to the invasion of Heglig.
South Sudan government spokesman Barnaba Marial Benjamin said earlier this month that Chinese and American investors want to build oil refineries in the South in the next six to seven months.
Benjamin said the refineries will help South Sudan process fuel for local consumption. South Sudan will also build a pipeline to the Kenyan coast and another to Djibouti through Ethiopia to be able to export its oil, he said. He said both projects were meant to make South Sudan independent of Sudan's fuel infrastructure and processing plants.
Kiir on Tuesday told Hu that he came to China because of the "great relationship" South Sudan has with China, calling it one of his country's "economic and strategic partners."
Both sides have tried to win Beijing's favor, but China has been careful to cultivate ties with each. Like others in the international community, China has repeatedly urged the two sides to return to negotiations.
The White House repeated its earlier condemnation of the Sudanese incursion and called for both sides to stop fighting and hold peace talks.
"Sudan must immediately halt the aerial and artillery bombardment against South Sudan by the Sudan armed forces," White House press secretary Jay Carney said Tuesday to reporters traveling with Obama to North Carolina. "Both governments must agree to an immediate unconditional cessation of hostilities and recommit to negotiations,"
He repeated Obama's warning to both sides that "there is no military solution" to their differences.
Associated Press writers Alexa Olesen in Beijing, Edith M. Lederer at the United Nations, Anne Gearan in Washington and Mohamed Saeed in Khartoum, Sudan, contributed to this report.