With his newly independent nation on the brink of war with its neighbor Sudan, South Sudanese President Salva Kiir went on a trip this week to seek help. But he didn’t travel to Washington, his country’s biggest aid donor. He went to China.

On Tuesday, he made his most forceful comment yet about the hostilities with Sudan in front of Chinese President Hu Jintao. Describing his visit as coming at a “critical moment,” Kiir told Hu that “our neighbor in Khartoum has declared war on the Republic of South Sudan.”

That Kiir left home at a time when Sudanese warplanes are bombing his nation, and just after Sudan’s President Omar Hassan al-Bashir vowed to “liberate” South Sudan from the “insects” who rule it, underscores China’s importance in a region that holds one of the most abundant reserves of oil in Africa.

“There must be some sort of relationship where China can play a positive role, even in this war,” South Sudan’s information minister, Barnaba Marial Benjamin, told reporters Tuesday. He said China’s relationship with both Sudans was like “a case of a husband with two wives.”

Kiir’s trip also highlights how vital the South Sudanese view China to their goal of exporting their significant deposits of oil without the assistance of Sudan, which controls the pipelines through which South Sudan’s crude passes.

For the Chinese, Kiir’s visit was the latest indicator of how deeply involved they have become in the bitter struggle, which has degenerated from a disagreement over oil transit fees to violent conflicts in and near oil installations in recent weeks.

China is the biggest player in the oil industry on both sides of the contested border, holding large stakes in oil fields, pipelines and other oil infrastructure. As part of the dispute, South Sudan has shut down production, cutting off a significant source of oil to China and jeopardizing billions of dollars in Chinese investments.

Each country has called on China to take its side, forcing China to inject itself into a struggle that has strained the boundaries of its long-standing policy of noninterference.

On Tuesday, Hu called for both sides to settle the disagreements through negotiations.

“The urgent task is to actively cooperate with the mediation efforts of the international community and halt armed conflict in the border areas,” Hu told Kiir during a meeting, according to Chinese state television.

“China sincerely hopes that South Sudan and Sudan can become good neighbors who coexist in amity and good partners who develop together,” he added.

Earlier in the day, Sudanese warplanes flew as far as 25 miles inside South Sudan and dropped at least eight bombs on several settlements, said Col. Philip Aguer, a military spokesman for South Sudan’s army.

Sudan also bombed a market near the oil town of Bentiu on Monday, killing two civilians and wounding 10, according to the U.N. mission in Juba, South Sudan’s capital.

The United Nations, the United States and other countries condemned Sudan for the bombings and urged both sides to head to the negotiating table.

The two sides fought Africa’s longest civil war before a 2005 peace deal paved the way for South Sudan to become independent last year. Since then, violence has steadily escalated over disputed border regions and oil revenue. Each side has accused the other of using proxy rebel militias to stage cross-border attacks.

Such violence has intensified since South Sudan’s takeover of the contested oil town of Heglig this month. Sudan and South Sudan each claim the area as its own; South Sudan on Friday announced its withdrawal from the town, but Sudan said its troops had forced out the South Sudanese troops.

“We have not declared war, but the SPLA is on maximum alert because if they attack, they will not catch the SPLA off guard,” Aguer told reporters, referring to South Sudan’s army. “If they don’t stop the bombardments, if they don’t stop the incursion into our territories, I assure you the SPLA is capable of retaking all of these areas that they are occupying by force.”

When asked why Kiir was in China at such a bellicose moment, Benjamin, South Sudan’s information minister, said the visit delivered a message to Bashir that Sudan is not China’s only friend and that South Sudan is becoming closer to China.

More important, Benjamin said, South Sudan wants China to finance development projects, particularly a pipeline through Kenya and refineries that would end the South’s dependency on Sudan’s pipelines and transit facilities. Benjamin said China appeared willing to provide South Sudan with soft loans and other forms of economic and technical assistance.

“Very few people these days give you money. And China has been known for this,” Benjamin said. “At this time, we need friends.”

Staff writer Colum Lynch in New York contributed to this report.