The government slashed windfall profit tax on export of diesel to its lowest of Rs 0.50 per litre and nil on jet fuel (ATF) while the levy on domestically produced crude oil was marginally increased, according to an official order. The levy on crude oil produced by companies such as Oil and Natural Gas Corporation (ONGC) has hiked to Rs 4,400 per tonne from Rs 4,350 per tonne, the order dated March 3 said. Crude oil pumped out of the ground and from below the seabed is refined and converted into fuels like petrol, diesel and aviation turbine fuel (ATF).