Unearthed, which is the environmental charity’s investigatory arm, found that BP has failed to report massive flaring emissions from one of its projects in Iraq – equivalent to the annual emissions of over 970,000 petrol cars.

BP jointly owns the Rumaila operating company but Unearthed said the firm denies responsibility for its emissions.

Gas is released during oil production and is typically captured for use in power generation or reinjected to force more oil out of the ground. But in some places, a lack of infrastructure means it has nowhere to go and is set alight or vented into the atmosphere instead.

In impoverished Iraq the vast majority of gas produced during oil production is flared, which exacerbates climate change.

According to Unearthed, big oil companies “routinely” underreport their emissions by omitting non-operated joint ventures from official climate impact reports.

It identified that flaring emissions are totally unreported in the Rumaila...