Environment activist Subhash Dutta moved the high court on Monday seeking the promotion of bio-diesel and withdrawal of a petroleum ministry circular barring the use of the fuel in vehicles. Bio-diesel is an eco-friendly fuel alternative for diesel engines. The petition stated that while the Centre had exempted bio-diesel from excise duty to make it popular, the petroleum ministry had issued a circular to the state governments asking them to stop the use of bio-diesel in vehicles. The activist claimed that though Calcutta Tramways Company had taken steps to use biodiesel in its fleet and the state environment secretary M.L. Meena had written to the transport department requesting wider use of bio-diesel, nothing could be done in Bengal because of the petroleum ministry circular.