NEW DELHI: In a bid to cool down edible oil prices, the government on Friday lowered the basic customs tax on crude edible oils by 10 percentage points. The duty change, effective Friday, is aimed at lowering the prices of palm oil, soyoil and sunflower oil. The move, which will reduce the effective duty to 16.5%, came amid a spike in prices, estimated at 17.4% in the retail inflation data for April.Prices of edible oils have heated up globally, negating the impact of a bumper mustard harvest in India. Mustard oil prices on average are 25% higher at over Rs 170 a litre, according to official data. Compared with a year ago, the average retail price of palm oil soared 34% to Rs 134 a litre on May 28, while sunflower prices were 30% higher. Soyoil has seen the smallest rise of 18% and sold for Rs 147 a litre in the domestic market.