Director Martyn Eustace described the initiative as "some sort of Orwellian attempt to impose misguided beliefs upon a general public who deserve to be treated better".

He warned that with around two thirds of computers in the EU left on permanently resulting in the energy use for data servers and IT equipment exceeding that of the airline industry, the true cost of electronic communication was too often left unchallenged.

"Encouraging the switch from paper-based to electronic communication, without the environmental facts, and without identifying and comparing the carbon impact of both media channels, is just irresponsible," he said.

"WWF's encouragement to ditch the printed word is not only misleading but highly dangerous."

He warned that the organisation's claims that its WWF file format "saves trees", was misleading when forests in Europe are growing at a rate of 1.5m football pitches every year and are 30% larger now than in 1950, and could be seen as grounds for a claim to the UK Advertising Standards Authority.

For the full text of Two Sides open response to the WWF, click here.