Greg Barker told controversial private adviser she was 'much more helpful' than Whitehall staff In another, he appeared to risk undermining one of his officials by accepting Ms Maes' criticisms of a report on a new heating scheme. He wrote to the unnamed official and Ms Maes: "Thank you Miriam, that is exactly right. [Official], please amend accordingly. Another email reprimands a civil servant for failing to put Ms Maes in charge of a project to make Whitehall more energy-efficient. Arguing the project needs more "strong commercial leadership," Mr Barker orders the official to "please rectify this with immediate effect." The emails come after Francis Maude, the cabinet minister, last month suggest many ministers are frustrated by passive resistance to new policies in the civil service. However, Mr Barker's emails to the private advisor have sparked accusations by Labour that he was too close to someone with outside business interests. The internal documents show he approved £5 million of taxpayer funding for a company linked to Ms Maes. The cash went to a non-profit company called Salix, which was a partner of Ms Maes's environmental consultancy, Foresee. She was copied into emails relating to the contract. Ms Maes says there is no commercial relationship between Foresee and Salix but they are part of the same "network." Mr Barker also held a series of meetings with one of the adviser's clients, Air Products, while the energy company was trying to win approval for a new energy from waste plant in Teesside. The company even "provided the minister with a hydrogen-powered car to travel between meetings" during an official business trip to the US. Mr Barker even intervened on behalf of Air Products with the Environment Agency, which was in charge of granting its pollution permits. During a meeting with the Environment Agency, Mr Barker raised the company's worries that the regulator did not "adequately understand" the benefits of the company's energy-from-waste technology. David Cameron is under pressure to order an official investigation, but his spokesman last night said Jeremy Heywood, the Cabinet Secretary, has already thoroughly examined the emails. Ms Maes has said she had disclosed her commercial relationships through her company, Foresee, to the department at all times. A spokesman for the DECC said the department has now improved the way it handles outside consultants. He said it was legitimate for Mr Barker to pass on concerns raised by a company in his sector. "The Minister raised this concern during a routine meeting with the Environment Agency," he said. It is part of his and the department's work to pursue issues raised by industry.