Drax power plant has continued to burn 250-year-old trees sourced from some of Canada’s oldest forests despite growing scrutiny of its sustainability claims, forestry experts say.

A new report suggests it is “highly likely” that Britain’s biggest power plant sourced some wood from ecologically valuable forests as recently as this summer. Drax, Britain’s single biggest source of carbon emissions, has received billions of pounds in subsidies from burning biomass derived largely from wood.