Royal Dutch/Shell has been forced to re-route a pipeline on its $12bn Sakhalin 2 project in eastern Russia because it threatened the survival of the western grey whale.

The Anglo-Dutch energy group halted building work on the offshore pipeline last year to allow for studies into its environmental impact. Shell's original route for the pipeline, which could eventually pump 140,000 barrels of oil a day, crossed the feeding grounds of the whale. Only about 100 western grey whales are thought to remain in existence.