NEW DELHI: Dissatisfied with Oil Minister Dharmendra Pradhan's reply on reduction of petroleum products, Opposition Congress, Left, TMC and SP today staged a walkout in Raya Sabha during Question Hour.Opposition parties contended that reduction in petrol and diesel prices domestically in the last six months was not commensurate with declining global crude oil prices and also questioned the justification of levying excise duty depriving consumers of their due benefit.Pradhan countered saying that after coming to power, the NDA government has reduced petrol and diesel prices by around Rs 10 a litre and Rs 9 per litre respectively and the need of levying additional excise duty was aimed at funding social welfare schemes as the last government had left the coffer empty.Opposition, however, contended that while reduction in crude oil prices was around 45 per cent, the cut in retail prices of fuel was only about 12 per cent.Tapan Kumar Sen (CPI-M) said even as international prices of crude oil had eased, the government deprived consumers of the benefit by raising the excise duty.The Minister said retail prices were calculated using a transparent formula and the difference between the price paid to the refinery and final retail selling price was on account of a host of elements including excise duty, state taxes, subsidies and freight.He said that the facts on oil prices being presented by opposition were misleading.The Opposition was not satisfied and stagged a walkout.