The government today approved conversion of three National Fertiliser plants to gas-based units at over 4,000 crore rupees investment. <br/><br/>An official statement said, the three feedstock conversion projects of NFL will be at its Nangal, Panipat and Bathinda units. The Cabinet Committee on Economic Affairs also allowed income tax exemption to subsidies given to these projects. <br/><br/>The conversion will also help units to modernise their existing ammonia plants and achieve better energy efficiency.<br/>