India's opposition parties Thursday threatened countrywide protests against a steep hike in the price of petrol while a key ally has demanded a reduction, dpa reported. State oil retailers at midnight Wednesday raised the price of petrol by 11.5 per cent, the steepest hike since the commodity was deregulated in June 2010. India imports 70 per cent of its oil and retailers say they were forced to raise prices given the fall in the value of the rupee. The currency has lost 13 per cent of its value since February and hit a new record low of 56.40 to the dollar in early trade Thursday.