The Eiffel Tower already complies with the law, turning off lights at 1am

The City of Light grew darker last night because of a French government drive to save energy and cut pollution.

A new law made it obligatory for businesses, stores and public buildings across France, including Paris, to turn off lights in shop windows and on façades between 1am and 7am.

Office lights must be switched off one hour after the last employee goes home under the plan, overseen by Delphine Batho, the Environment Minister.

Companies that fail to respect the law face fines of €750 (£640) per night, though officials say there will be a bedding-in period before the first penalty notices are issued.

The move could signify radical change for the many French companies that leave lights on all night through negligence, and for