Royal Dutch Shell is facing allegations that it was heavy handed in influencing a supposedly independent environmental report on one of the world’s largest oil and gas extraction projects.

A report in The Observer yesterday cited email evidence that allegedly shows Shell looked to downplay some of the environmental criticism included in the review of the $22bn Sakhalin II Project in Russia – which has now received the bulk of the funding it required for work on the project to begin.

The review was conducted by environmental consultancy AEA Technology.

The emails, which were released to the paper following a Freedom of Information request, show that Shell tried to disperse damning evidence throughout the report, as well as downplay the effects of the project on local wildlife, particularly whales.

The exchange reveals concern from an unnamed party, thought to be a government agency, that Shell was “stage managing” the report in order to minimise the impact of environmental concerns.

A spokesman for AEA Technology insisted the report was produced independently, while Shell also defended its involvement, claiming it had not placed any undue pressure on the consultancy to water down its findings. “The opportunity for Sakhalin Energy and its shareholders to provide comments on a draft report of this kind is routine and designed to ensure accuracy,” said a spokesman for Shell. “The findings contained in AEA Technology’s report are entirely theirs.”

However, green groups – already angered by Shell’s recent decision to exit the London Array offshore wind project and increase investment in Canadian tar sands extraction – expressed concern at the news.

Speaking to The Observer, Doug Norlen, policy director of US-based Pacific Environment, said that not only did the AEA report list Sakhalin Energy as its client, when it is meant to be fully independent, but that Shell was also guilty of stage-managing the whole process. “They set the agenda, scheduled meetings and even participated in the editing of sections,” he said. “I believe this to be a stark and vivid example of manipulation. In addition to skewing the review it destroys the pretence that banks have used ethical considerations before deciding whether to fund the project.”