(Adds details on firms operating in South Sudan's Unity State, comment from minister)
JUBA, Dec 19 (Reuters) - About 200 oil workers who sought refuge at a United Nations base in Unity State, a South Sudanese oil-producing region bordering Sudan, are expected to be evacuated by their employers, a United Nations official said on Thursday.
"We expect their presence to be temporary because we understand that the company they are working for will be arranging for transport to get out of Unity State," Joe Contreras, U.N. spokesman in South Sudan, told Reuters, without saying which company they worked for.
The oil companies operating in Unity State are China National Petroleum Corp, India's ONGC Videsh and Malaysia's Petronas.
Information Minister Michael Makuei Leuth on Thursday said South Sudan's oil producing areas have not been affected by the conflict, in which up to 500 people have been killed since fighting started on Sunday evening.
"There is no fighting in the oil fields. They are peaceful. The oil is flowing as usual," Leuth told Reuters. (Additional reporting by George Obulutsa, Writing by Drazen Jorgic; editing by William Hardy)