Updated

The president of the world's newest nation, South Sudan, has cut short a visit to China due to the rising threat of war at home.

China's top legislator, Wu Bangguo, said during talks Wednesday with South Sudan President Salva Kiir that it was unfortunate Kiir was forced to shorten his stay and cancel a planned trip to Shanghai due to "domestic issues."

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.

Sudanese warplanes bombed a South Sudanese market and an oil field Monday, killing at least two people, and dropped eight more bombs Tuesday.

Kiir told Chinese President Hu Jintao on Tuesday that Sudan had "declared war" on his country. The comment signaled a rise in rhetoric between the two sides, which spent decades at war with each other, though neither country has officially declared war.

Kiir originally planned to spend five days in China, a key economic and strategic partner for the newly independent country. It remained unclear exactly when he would return to South Sudan.

China's energy needs make it deeply vested in the future of the two Sudans. Beijing is uniquely positioned to exert influence in the Sudanese conflict, given its deep trade ties to the resource-rich south and decades-long diplomatic ties with Sudan's government in the north.

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 is also reported to be seeking Chinese financing for new pipelines, including one to the Kenyan coast and another to Djibouti through Ethiopia that would allow it to export its oil. The projects are meant to make South Sudan independent of Sudan's fuel infrastructure and processing plants.

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.