State-owned oil companies today raised petrol prices by Rs. 2.50-Rs. 2.54 per litre, the second hike in a month, on back of rising crude oil prices. Indian Oil Corp, the nation's largest fuel retailer, will raise petrol prices by Rs. 2.50 per litre with effect from midnight tonight, while Hindustan Petroleum Corp Ltd (HPCL) would hike rates by Rs. 2.54 a litre, an industry official said.