Energy minister asked about permit application for adviser's client Greg Barker, climate change minister. New revelations about Air Products raises further questions about his judgment in allowing Miriam Maes to pursue her consultancy client's interests while also being paid as a Decc adviser. Photograph: Paul Hackett/Reuters Greg Barker, the climate change minister, personally asked the Environment Agency (EA) about a permit application being submitted by a US energy company that was also paying one of his departmental advisers as a consultant, the Guardian has learned. Emails released under freedom of information legislation show that Miriam Maes, a paid "delivery adviser" at the Department of Energy and Climate Change (Decc) who was also acting at the same time as a consultant to the US energy firm Air Products, helped to engineer a meeting between Barker and Air Products the day before the minister went to visit the Environment Agency for a regular "update." On 6 February 2011, Maes emailed Barker - without copying in a Decc official as she was meant to - requesting a meeting with "one of my clients Air Products." She added: "I will send a formal request in through [redacted] but could you give it a gentle nudge if needed?" She also forwarded Air Products' "meeting objectives," which included "Highlights of Tees Valley Project" and "Path forward." Less than an hour later, Barker replied: "Of course, let's get it in the diary but let's have a chat rather than email." Maes replied: "Ok understood!" A meeting took place between Air Products, Barker, Maes and Decc officials on 1 March. At the meeting with the EA the following day, Barker asked about the permit application that Air Products needed, in addition to planning consent, to receive the green light to build the world's largest renewable energy plant on Teesside. Six weeks later Maes emailed Barker, again without copying in a Decc official, to say: "Although it is a while ago, were you able to discuss the Air Products' situation with [redacted] from the Environmental Agency?" Just under three hours later, Barker replied: "I did!" Asked by the Guardian if she had asked for Barker to personally inquire about the permit, Maes said: "I absolutely never asked Greg Barker, ahead of his March 2nd 2011 meeting with the EA or any time before or after about Air Products' permit application for the Teesside plant." She also played down her relationship with another company, Salix, which secured a £5m contract from Decc and was listed on her website as part of a network of partners. "The DECC officials had prepared as usual a ministerial briefing note prior to the meeting with Salix, including the recommendation [to award a contract]," she said. I did not have any input into this briefing note prior to the meeting and was only asked to join the meeting with Salix at the last moment. When asked for my views in the meeting with Salix, I said that I agreed with the recommendation from the Decc officials. Both Maes and Salix insist no money changed hands between them. But the revelations about Air Products raise questions about the appropriateness of Barker's relationship with Maes and in particular his judgment in allowing Maes to pursue her consultancy client's interests while also being paid as a Decc adviser. Barker met Air Products three times in 2011, the company says, and featured at least twice in publicity photographs taken for the company. He also agreed to a positive quote, drafted by Air Products in his name and forwarded for his attention by Maes, to be used in an Air Products press release in August 2011, announcing that the Teesside plant had been granted planning permission. Maes emailed Barker, without copying in an official, on 10 August 2011 to say: "Many thanks for accepting the quote!" Labour has called on the prime minister to conduct a fresh investigation into the affair following revelations published in the Guardian this week. On Wednesday, David Cameron said the cabinet secretary and Decc's permanent secretary had already looked into whether Maes was properly appointed as an adviser and concluded nothing was untoward. However, it is still unclear when this investigation took place, if it examined all the newly released emails or whether its remit included Barker's judgment in dealing with Maes, a former personal adviser to him before he became a minister in 2010. Asked by the Guardian to explain the Air Products "situation," referred to in Maes's email to Barker on 18 March 2011, an EA spokeswoman said: "The EA's chief executive Paul Leinster and chairman Lord Smith meet with Decc ministers to update them on our frontline work, such as the administration of carbon trading schemes. At the meeting on 2 March, 2011, with Greg Barker we were asked a question about a proposed permit application by Air Products for a gasification plant on Teesside that aimed to use new technology. We provided factual information about the permitting process. The spokeswoman later confirmed that it was Barker asked EA the question. She said: "The minister wanted clarification that the new gasification technology was understood in relation to the permitting process. We provided a factual update about the permitting process. She added that the permit was granted by the EA in April this year after a "robust 11-month assessment in line with strict terms of the Waste Incineration Directive. The resulting permit sets limits on emissions and lays out reporting and monitoring requirements to ensure the environment and local community are protected. When it opens in 2014 on the site of a former ICI factory near Billingham, the 49MW energy-from-waste plant will provide power for up to 50,000 homes in the north-east by burning 350,000 metric tonnes of non-recyclable waste from landfill each year. People close to Barker defended his actions. The email from Barker suggesting that he and Maes should talk about Air Products rather than email was sent because Maes often sent several long emails: "Barker could not see them on a BlackBerry and found it quicker to discuss issues instead to stop her filling up the inbox," said a person close to the minister. Barker had raised the Teesside project with the EA because he was worried its knowledge of the technology was "out of date." Sources close to the minister also defended Maes, saying: "[She] was certainly the most qualified woman in the whole distributed energy field in London. We were extremely lucky to have her on board."In reference to Barker's offer to "nudge" officials about an invoice, Barker had not pressed officials to pay the money, only to make sure it was dealt with. An Air Products spokeswoman said: "During the period February 2010 until November 2011, Air Products engaged Miriam Maes as a consultant to advise us on the UK energy market which included engagement with potential power purchasers in the UK. As part of this process, we met with Greg Barker in March 2011 following a formal meeting request to his private secretary. We had first established from Mrs Maes that there was no legal or ethical barrier to the minister being briefed on a new energy-from-waste technology within his ministerial portfolio. Further separate meetings were held with Mr Barker as part of his Green Trade Mission to the USA in March 2011, organised by UKTI and again at the Conservative Party Conference in October 2011."The spokeswoman added: "The [first] meeting [with Barker] took place at 4pm on Tuesday, 1st March 2011 at which Greg Barker and Miriam Maes were present along with civil servants from Decc. The meeting was held at Decc's office on 3 Whitehall Place. A Decc spokesman said: "The minister raised this concern during a routine meeting with the Environment Agency. It is part of his and the department's work to pursue issues raised by industry.