LONDON May 1 South Sudan's chief negotiator on Tuesday criticised China, which backs both Juba and Khartoum, for not taking a more robust role in resolving a crisis between the neighbours that has halted oil output and may tip them back into war.
China is one of Sudanese President Omar Hassan al-Bashir's strongest supporters and has had to play a delicate balancing act with South Sudan, which seceded from the north in July and with which Beijing has major business and oil interests.
South Sudan gained independence in July under a 2005 settlement deal that ended two decades of civil war.
The Asian giant pledged $8 billion in development funds when South Sudanese President Salva Kiir visited Beijing last week.
China is the biggest buyer of South Sudan's oil and last year it imported 260,000 barrels per day (bpd) of crude from the two countries, according to the International Energy Agency.
Speaking at London think-tank Chatham House, negotiator Pagan Amum said China's balancing act was too cautious.
"Honestly speaking, China has not succeeded. They appointed a special envoy who came very late and also who was very cautious," Amum said.
"By trying to move away from Khartoum so as to get closer to South Sudan and trying not to get too close to South Sudan so as not to cause displeasure to Khartoum ... neither Khartoum nor Juba will be happy with China," he said.
At the same time, China, traditionally seen as Bashir's ally at the Security Council, is resisting Western moves at the United Nationls that would threaten both sides with sanctions if they fail to halt the conflict.
"We would want to see China playing a more active role. Their role has not been very active. Maybe China also (needs) to catch up its foreign policy with its international position, having huge investments abroad," Amum said.
"They definitely need to be more proactive, especially in relation to Sudan and South Sudan," he said.
The two countries have been arguing over oil transit fees, border demarcation, and citizenship. Last month the dispute broke out into cross-border fighting along the 1,800 km (1,100 mile) badly demarcated border.
South Sudan shut down its production of crude oil, over what it said was the illegal seizure of the oil by Sudan. Sudan says it seized the oil to make up for unpaid fees.
Amum repeated previous statements that Juba would no longer consider sending its oil through Sudan because of the seizures, saying such an option is, "out of negotiations".
When landlocked South Sudan seceded from Sudan last year, it took three-quarters of the region's crude production, while the pipelines to export the oil are mostly in Sudan.
Juba is considering building a pipeline through Kenya to a port there to bypass the north, and has asked China to consider joining the project.
"As long as this is the mindset in Khartoum, the easiest way to export our oil is through an alternative pipeline," Amum said on Tuesday. "It is clear to the Chinese as well."
Analysts have expressed skepticism about the viability of a new pipeline, given security concerns and the dwindling amount of South Sudanese oil it could carry.
According to BP's 2011 energy statistical review, Sudan had proved reserves of 6.7 billion barrels at the end of 2010, with a daily production of 486,000 bpd. (Reporting by Yeganeh Torbati; Editing by Yara Bayoumy, David Clarke, Ron Askew)