STATE-run Nigerian National Petroleum Corp said on Tuesday it has begun preliminary talks with South African investors planning to set up an oil refinery in Nigeria. The investors plan to build and operate a refinery with a concession to lift Nigerian crude oil. The capacity of the plant is not yet known. The three-member South African delegation included Mike Foley of Gallagher Power Force, Paul de Swadt and Philips Moller of Thyse SA. Last month, two South African companies, Engen and Loita Capital tendered for a controlling stake in Nigerian companies.