KHARTOUM - Sudan fears that conflict in South Sudan, where rival army factions have clashed, could affect the flow of oil through Sudanese territory and in turn hurt Khartoum, the Sudanese army spokesman said on Thursday.

Colonel Khaled Sawarmi told Reuters that if fighting spreads from oil-rich Jonglei state, northeast of the South Sudanese capital Juba, to areas that border Sudanese territory, Sudan would face a significant security threat.

"The oil in the South goes through the Sudanese border, and stopping the oil would affect negatively on Sudan," he said. "We are very worried about an escalation in the situation."

Landlocked South Sudan, which gained independence from Sudan two years ago, pays fees to Sudan to refine its crude and export it from Port Sudan on the Red Sea, making the oil an important source of income for both states.

Five days of fighting in South Sudan between soldiers loyal to former vice president Riek Machar, from the Nuer group, and troops backing President Salva Kiir, a Dinka, has killed up to 500 people but has not hurt oil production.

About 200 oil workers who sought refuge at a United Nations base in Unity state, which borders Sudan, are expected to be evacuated by their oil firm, the United Nations said on Thursday.