Caroline Jackson, Conservative MEP and party environment spokesperson, is facing questions about a conflict of interest over her relationship with various private companies.
Ms Jackson is a member of the European parliament's environment, consumer protection and public health committee, including a stint as chairperson between 1999 and 2004. But concerns have been raised over her position on the board of car company Peugeot Talbot and as paid consultant to food giant Mars.
While Ms Jackson resigned her Peugeot directorship upon becoming chair of the committee she maintained her role with Mars, despite being responsible for committee reports on product safety and food additives. The committee also dealt with issues pertaining to the sugar levels in sweets.
The revelations come in a new report published by pressure group SpinWatch, who have compiled a dossier of MEPs' interests despite facing severe obstacles in the form of European parliament regulations. As Tamasin Cave, a transparency activist, says in an opinion piece for politics.co.uk today, MEPs' interests are only declared in their host language, and are kept in a room in Brussels from which they cannot be removed or photocopied.
Ms Jackson's position is further complicated by her role as paid advisor to Shanks, an independent waste company based in the UK and the Netherlands.
Despite this, Ms Jackson acted as rapporteur on the environment committee for the revision of the waste framework directive, investigating the issue and reporting back to the group.
The head of the company's environmental advisory board (EAB), professor James Bridges, wrote: "The EC waste framework directive is also being revised and as the MEP within the European parliament responsible for the revision of the directive, EAB member Caroline Jackson was able to keep us updated on progress during the year.
"This will have far-reaching implications for waste management and the EAB will consider its impacts on Shanks activities in the UK and mainland Europe."
Ms Jackson's unique position meant she was rapporteur for a European parliament report whilst also acting as a consultant to a company which could be impacted by the report.
Ms Jackson maintains Shanks has no interest in incinerating waste - the main subject of her report - saying: "There is no conflict of interest because Shanks is not really involved in the kind of waste treatment activities that are touched on by the waste framework directive."
But Shanks' website says the company "remediates PCB and pesticide contaminated soil through high temperature incineration at dedicated facilities in the UK and the Netherlands".
A Tory spokesman contacted by politics.co.uk poured cold water on the findings, however.
"Caroline Jackson has made no secret of her association with Shanks," he said.
"She's not on the board of directors, she's an advisor. And in all sessions she's made it clear to the parliament and the committee her association with this company."
The SpinWatch report - Too Close for Comfort? - is designed as an opening salvo in attempts to focus attention on MEPs' various financial and political interests.