Jul. 13, 2009 (China Knowledge) - PetroChina International Co Ltd, a wholly-owned subsidiary of PetroChina<601857><0857><PTR>, the nation's top oil producer, in June obtained approval from the National Development and Reform Commission (NDRC), the nation's top economic planning agency, to buy a 49% stake in a refinery belonging to Japan-based oil giant Nippon Oil, the NDRC said o
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