South Sudan's military spokesman Col. Philip Aguer said that Sudanese Antonovs dropped eight bombs overnight between 11 p.m. and 1 a.m. in Panakuac, where he said ground fighting had been ongoing since Sunday. Aguer said he has not received information on whether there were casualties from the attack because of poor communications.
On Monday, Sudanese warplanes bombed a market and an oil field in South Sudan, killing at least two people after Sudanese ground forces had reportedly crossed into South Sudan with tanks and artillery.
South Sudan seceded from Sudan last year as a result of a 2005 peace treaty that ended decades of war that killed 2 million people. The countries have been fighting over the sharing of oil revenues and a disputed border.
South Sudan's President Salva Kiir on Tuesday during a visit to Beijing told China's president that attacks by rival Sudan amount to a declaration of war on his country.
There has yet to be a formal declaration of war by either of the Sudans, and Kiir's remark, made during talks with President Hu Jintao, signals a ratcheting up of rhetoric between the rival nations which have been teetering on the brink of war.
Kiir arrived in China late Monday for a five-day visit lobbying for economic and diplomatic support. He told Hu 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 broke away from its neighbor and became independent last year. The two countries have been unable to resolve disputes over sharing oil revenue and determining a border. Talks broke down this month after attacks started between the two countries with South Sudan invading the oil-rich border town of Heglig, which Sudan claims it controls.
Following international pressure, South Sudan announced that it has withdrawn all its troops from Heglig but Sudan claimed its troops forced them out.
Sudanese President Omar al-Bashir has vowed to press ahead with his military campaign until all southern troops or affiliated forces are chased out of the north.
In a fiery speech to a rally Friday, after he declared the liberation of Heglig, al-Bashir said there will be no negotiations with the "poisonous insects" the Sudan People's Liberation Movement. At the time 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 Sudan's capital, Khartoum, of stealing hundred millions of dollars of oil revenue. Sudan responded by bombing the South's oil fields.
Earlier this month, South Sudan government spokesman Barnaba Marial Benjamin said 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 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."
China's energy needs make it deeply vested in the future of the two Sudans, and 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.
Both have tried to win Beijing's favor, but China has been careful to cultivate ties with each nation. Like others in the international community, China has repeatedly urged the two sides to return to negotiations.