Sue Welland, founder of The CarbonNeutral Company - which measures carbon output and then offsets it via energy-saving projects - said that instead of being a ‘thought-leader', the PR ­industry is trailing even other marcoms disciplines in adopting carbon neutrality.

Of the top ten PR agencies - as ranked by PRWeek -  none is ‘carbon-neutral', although the Bell Pottinger Group expects to be shortly.

‘It is staggering that the PR industry has failed to grasp the climate-change nettle in a "walk the walk" way,' she said. ‘Ad agencies, on the other hand, have taken time to understand issues and take action to reduce emissions.'

The attack comes just a week after the Stern report for Government on ­climate change. The Carbon Trust, the ­government-funded body, told PRWeek that UK business should do all it can to improve its green record.

PRCA director-general Patrick Barrow said PR agencies were striving to help reduce carbon emissions, but the task of becoming carbon-neutral was onerous.

‘You can't assume that because not many are working with The CarbonNeutral Company, nothing is being done,' he said. He added: ‘It is very difficult for PR agencies, and any marcoms agency, to work out their carbon footprint because they would have to ­factor in polluting clients.'