Chinese Vice President Xi Jinping on Tuesday urged Sudan and South Sudan to resolve their differences "at an early date", as Beijing seeks to end a crisis between the two neighbours over oil.

Xi also urged Khartoum to take "concrete measures" to ensure the safety of Chinese nationals and companies operating in the African country, the official Xinhua news agency said, amid fears of renewed conflict in the region.

South Sudan split from the north last year, but while it has most of the oil, Khartoum controls the pipeline and has access to the sea, sparking a furious argument.

Last month, Juba vowed to halt oil production of around 350,000 barrels per day until Sudan repaid 2.4 million barrels of southern crude it confiscated from pipelines running through the north to its Red Sea port.

"China hopes that Sudan and South Sudan... continue to keep patient and properly handle the relevant dispute at an early date," Xi told visiting Sudanese Foreign Minister Ali Karti.

Karti told Xi, who is likely to succeed President Hu Jintao during a major leadership transition that begins later this year, that Khartoum would resolve the crisis through negotiations.

South Sudan said last week it had expelled the Chinese head of the country's largest oil firm Petrodar on charges of colluding with Khartoum to "steal" millions of barrels of its oil.

Before the shutdown, China relied on South Sudan for nearly five percent of its oil.