A Chinese envoy was in Khartoum for talks on Sunday after his country backed a UN resolution that aims to halt border fighting between Sudan and South Sudan.

Zhong Jianhua arrived in the Sudanese capital on Saturday and was expected to leave on Sunday night after talks with government officials, a Chinese official told AFP.

"I think mostly it's about the current situation between the two Sudans," said the official, who did not wish to be identified.

From Khartoum, Zhong will head to Addis Ababa and then to the South Sudanese capital Juba, the official added.

Zhong was to hold talks later on Sunday with Sudan's Foreign Minister Ali Karti, the spokesman for Khartoum's foreign ministry said.

China backed a unanimous May 2 UN Security Council resolution ordering Sudan and South Sudan to halt weeks of border fighting which raised fears of all-out war.

Despite the ceasefire call, Sudan's army said last week there had been renewed combat along the disputed frontier, while the South said it again came under Sudanese air attack.

The UN resolution said the two countries must resume by this Wednesday stalled African Union-led talks, which were held in the Ethiopian capital Addis Ababa, to settle issues unresolved after South Sudan separated last July under a peace deal that ended 22 years of civil war.

The issues include oil payments, the status of each country's citizens resident in the other, disputed border areas and the contested Abyei region.

Analysts say China has been balancing its support between old ally Sudan and newly-independent South Sudan, which was the source of five percent of its oil until a shutdown in January.

South Sudan separated with about 75 percent of the former united Sudan's oil production, but Juba still depended on the north's pipeline and Red Sea port to export its crude.

The protracted dispute over fees for use of that infrastructure was at the heart of tensions which brought the two countries to the brink of all-out war and led South Sudan to halt its crude production.

South Sudan's President Salva Kiir visited Beijing in April and received an $8-billion loan for infrastructure development in the impoverished country.