The warning was prompted by last week’s announcement the supermarket was relaunching some of its ranges of prepared meals, snacks and sandwiches as part of a new "Waitrose Way Commitments" corporate social responsibility initiative.

A Waitrose spokeswoman said: "The relaunch of ranges of prepared meals and snacks was a great opportunity to relaunch the packaging. Our in-house graphic design team and internal packaging team will have worked very closely with suppliers."

The supermarket is to reduce sleeve sizes, increase plastic window sizes and remove trays in a bid to cut packing by 100 tonnes every year. But previous attempts by others to reduce packaging have backfired, experts warn.

Chesapeake head of marketing Bob Houghton said: "This is very ambitious but will it work? People have tried reducing packing before, such as toothpaste cartons, only to find the product didn’t display very well and have to revert back quickly.

"Packaging is there for a reason, such as protection and display of information required by law. It also adds gift value, so if you take it away you take away some of the value, which sounds odd for Waitrose, which sells high-value items."

He added: "Impact on the industry is hard to say; inevitably there will be lower volumes for the sector. It could prompt innovation from packagers, but I’m concerned this is a green initiative that makes good headlines but might not deliver."

BPIF Cartons general manager Neal Whipp said: "Waitrose is likely to increase food waste in preparation by reducing packaging. It’s always possible to cut packaging but there will be consequences: packaging is not waste, it’s part of the product. Reductions in packaging weight have already been carried out by most manufacturers."

The Menu from Waitrose has been relaunched with new packaging for all 49 products in the range. Width of sleeves has been decreased to cut 33 tonnes of packaging per year, equivalent to a 20% overall weight saving.

"It is also the first time that a retailer has introduced aluminium trays, lacquered both internally and externally, for ready meals, allowing customers to cook and serve meals in the same tray and are still able to recycle it after use," said the retailer's spokeswoman.

The Good to Go range of 190 snacks meanwhile was re-launched to cut packaging by 25 tonnes per year. Changes include increasing the size of clear windows to allow better visibility of the product, cutting 11 tonnes of packaging per year.

Pre-printed bags for fruit portions were also changed, saving 60% of the weight by taking off the label. Flow wrap has been rolled out for all meat including lamb and pork. Removing the tray saves 38 tonnes of packaging per year - a 70% saving.

Waitrose packaging and reprographics manager Karen Graley said: "We are always working hard to reduce packaging where we can, to decrease the waste reaching our customers’ bins and ensure they can recycle as much as possible.

"Relaunching a range is a fantastic opportunity to do this and cutting packaging by nearly 100 tonnes per year is a great result to have achieved on our journey to halving packaging by 2016."

Waitrose head of sustainability and ethical sourcing Quentin Clark said: "As a nation we’re getting busier, and lack of time means we need to be able to trust the retailer we are using.

"So when creating these pledges we made sure the emphasis was on how we we're being part of the solution, now and in the future - we want it to be really easy for our customers to know we’re doing the right thing."