A leading British investor today joins the chorus of concern about a headlong flight into biofuels as a solution for global warming by saying companies involved in the sector could jeopardise future profits by not carefully considering the long-term impact of what they are doing. Sustainability criteria must be built in to the supply chain of any green fuel project to ensure that there is no adverse effect to the surrounding environment and social structure, Co-operative Insurance (CIS), the investment arm of the Co-op, says in a report.