Easter egg manufacturers have not gone far enough to reduce packaging and improve recyclability, a report has concluded.
The annual survey by Liberal Democrat MP Jo Swinson found the percentage of Easter egg boxes taken up by chocolate was 38% - the same figure as last year.
The study found a number of manufacturers are not using widely recyclable materials for packaging, meaning much of it still ends up in landfill sites.
Luxury eggs from Thorntons, Baileys and Marks & Spencer continued to rely on plastic packaging that is not recyclable in most local authorities, leaving consumers confused as to what should be binned or recycled, according to the report.
It singled out a Sainsbury's Taste the Difference chocolate egg for wrongly bearing the "widely recycled" symbol.
However the "big three" confectionery companies - Nestle, Mars and Cadbury - used packaging made from widely recyclable materials such as cardboard for their medium-sized eggs, with Nestle becoming the first major confectioner to make its full Easter range 100% recyclable.
Swinson said: "Since launching this report in 2007 the main chocolate companies have acted to reduce their packaging and improve recyclability.
"However there are still a number of companies who rely too much on plastic and are sitting on their laurels.
"A few manufacturers are hiding behind green credentials with packaging that isn't easily recyclable by the majority of consumers.
"Manufacturers know that their plastic boxes aren't widely recycled and yet they continue to use them, despite other companies showing how Easter eggs can be packaged with a mind to efficiency and recyclability."
Environment Secretary Caroline Spelman said: "Nobody wants broken Easter eggs but excessive packaging costs everyone money and creates unnecessary waste, which is bad for the environment."
Many easter egg retailers defended their practices after the report was released.
A Sainsbury's spokeswoman said: "We take our responsibility to minimise our impact on the environment very seriously and we have reduced our Easter egg packaging by 57% since 2008. This is part of our wider commitment to reduce our own packaging by a half compared to 2005."
An M&S spokeswoman said: "M&S is committed to packaging reduction and has already met its Plan A target of reducing its packaging by 25%, a year ahead of plan.
"This year we will use 6% less packaging on our Easter eggs than last year. Eighty per cent of our carton board is now from recycled or sustainable sources and 100% of the PET plastic we use is recyclable too. Overall, 91% of all our food packaging is now recyclable."
A Thorntons spokeswoman said: "Thorntons has once again made reductions to its Easter packaging this year as part of its continued commitment to reduce the environmental impact of its products.
"Thorntons reduced its Easter packaging in 2009 by 22% and has continued to make reductions every year since then. This Easter season Thorntons has reduced its packaging by a further 9.69 tonnes."