Beijing said Monday it was sending an envoy to try to resolve a row over oil exports between Sudan and South Sudan, where China has substantial oil interests.

Liu Guijin, a special representative of the Chinese government on African affairs, will visit Sudan and South Sudan in the coming days to promote talks between the two countries, the foreign ministry said.

Energy-hungry China relies on South Sudan for nearly five percent of its oil. Last week, Sudan said it was blocking oil exports from the landlocked south from flowing through its terminals on the Red Sea in a row over transit fees.

After a rare intervention by Beijing, Khartoum's chief oil negotiator said exports would be allowed to continue, but the north would take a cut of the south's oil as "payment in kind" until an agreement on transit fees was reached.

"China is concerned about recent tensions between Sudan and South Sudan, in particular the stalled negotiations over the oil issue," foreign ministry spokesman Hong Lei said as he announced the visit.

"Maintaining normal oil production serves the common interests of the two countries."

The state-run China National Petroleum Corporation (CNPC) has pumped billions of dollars into developing oilfields in Sudan, 80 percent of which lie in the south, before South Sudan seceded in July.

Beijing is a key ally of Khartoum, which has suffered from US economic sanctions since 1997, and has sought to maintain good relations with both countries.

China is a a major military supplier to the Khartoum regime, as well as one of the biggest buyers of Sudanese oil.