The company said its START programme will use blockchain to help customers verify the environmental, social and governance standards involved in their aluminium purchases.

Aluminium sold by Rio Tinto under START will be labelled digitally with the information, in a style the company compares to nutritional information on food packaging.

Companies that use this aluminium can then use the labels to highlight their carbon-free commitments.

"Our vision is that our customers can showcase the sustainability of the aluminium they purchase from Rio Tinto to their consumers, delivering full value from our responsible production,"  said Rio Tinto Aluminium chief executive Alf Barrios.

"START will help customers meet the demand from consumers for transparency on where and how the products they purchase are made".