The Centre introduced E20, a blend of 20 per cent ethanol and 80 per cent petrol, as part of efforts to reduce vehicular emissions and cut dependence on crude oil imports.
Jairam Ramesh said ethanol production from sugarcane, rice and maize places heavy pressure on water resources and urged the Centre to adopt more sustainable feedstocks.
The letter had raised concerns that contamination in E20 fuel was causing vehicle-related issues, with SIAM citing the need for further authentication of the findings.