According to the probe, lead was found in areas adjacent to the cathedral, noting that it was “very localised” and “notably on premises that may have been standing open at the time of the fire, and where dust had settled”.

The police added that public areas under threat for potential lead contamination have been shut down and will not be reopened until lead levels stabilise.

The announcement comes as the French environmental campaigners, Robin des Bois, reported that some 300 tonnes of lead from Notre Dame’s roof and spire had melted in the conflagration. The group called on the authorities to detoxify the debris produced in the disaster.