When an empty oil tanker drifted onto a Liberian beach, it disturbed golden shores usually troubled only by baby crabs, and raised rumours of everything from an Islamist invasion to a ghost crew.

For more than a decade, communities in Liberia have struggled against palm oil company Golden Veroleum Liberia (GVL), which has razed more than 1,000 hectares (almost 2,500 acres) of rainforest, ...