EU plans to introduce an 'omni' label for environmentally friendly food products are unworkable because "the science isn't there", a damning new Defra funded review of food labels has found.

The scientific methods used for mapping the environmental impact of many resources used in food production were not yet good enough to base a credible label on them, claimed the research carried out by the University of Hertfordshire, the Food Ethics Council and the Policy Studies Institute.

Scientists studied existing eco-labels and environmental claims on products and the underlying standards used to measure them. They also considered the potential use of an 'omni-label' that encompasses a range of environmental benchmarks an idea being mooted at EU level at the moment.

"Our view is that the science isn't there on most of the environmental impacts it's not there for covering air quality or water quality in a robust manner that you could use in a label," said Kathy Lewis, head of the agriculture and environmental research unit at the university. The exception to this was carbon footprinting, which used a widely accepted scientific methodology.

There would be no point in introducing an omni-label until the science was robust on all fronts, she ­added. "It's not right to say to somebody 'you should be buying this' if you can't prove it and we can't prove it because we don't understand the technologies. If the science isn't there, someone might come along and challenge it and then you are in a real mess."

Lewis stressed the conclusions were those of the research team and not those of Defra, which is ­expected to publish a report based on the findings later this year.

Defra commissioned the research earlier this year (at a cost of £68,010) in ­preparation for discussions about a planned EU ­research project into the ­application of an 'environmental' label for food ­products.