iPhone maker Apple and BlackBerry outfit RIM are refusing to take part in the UK's first ever scheme to rank the environmental impact of mobile phones.
Mobile network O2, which launched the scheme today, says it will still include 93 per cent of all the devices it supplies.
The rankings have been launched in conjunction with sustainability advisers Forum For The Future. Each device has been given a rating of between zero and five, which takes take into account a range of eco-factors, including what they're made from, how energy-efficient they are, their likely lifespan, and how easy they are to re-use and recycle.
The rankings also include other ethical considerations, such as labour standards and employee safety. The full details are explained in a PDF here.
Apple declined to comment on why it had decided not to join the voluntary labelling scheme, but drew the attention of consumers to its own online environmental reporting.
Rivals such as market leader Nokia also publish environmental information online in this way, but have agreed to take part in the scheme. Other participants include Sony Ericsson, Samsung, LG and HTC.
Research In Motion (RIM) which makes the popular BlackBerry device, also declined to join the scheme - but has promised to do so next year, perhaps so that it can clean up its act before having its green credentials subjected to public scrutiny.
The rankings are based on manufacturers' responses to 63 questions. According to the ratings, Sony Ericsson's Elm is the greenest phone, with a score of 4.3 out of 5. Palm's Pre Plus trailed in last with 2.7.
One of the reasons suggested for the two companies' reluctance to join the scheme has been the fact that the ratings look at the company's environmental record as a whole, which is given an 11 per cent weighting in the overall ranking.
"Transparency is always an issue for consumer electronics companies, who claim that providing too much information gives away competitive advantage. But consumers also deserve to know the full story," Gary Cook, IT sector analyst for Greenpeace International told The Guardian newspaper.
"While Apple has recently made important strides in eliminating toxic chemicals from its products and the reporting of their environmental footprint, it still lags behind others in transparency."
There are signs that consumers themselves are demanding to know more about the eco-friendliness of the phones theys use. Of the people surveyed for O2, 11.5 per cent said sustainability had a "strong influence" on their choice of model.