Four of the country's biggest suppliers launched major bids this week to ramp up their green credentials.

Cadbury Schweppes, PepsiCo, Coca-Cola Enterprises and Associated British Foods announced programmes to cut their carbon emissions and packaging use.

Cadbury is arguably the most ambitious of the four. The confectionery manufacturer has pledged to reduce its current global carbon emissions by 50% by 2020 as part of its new 'Purple goes Green' initiative.

In the week that Trading Standards called for food companies to be fined £50,000 for using excess packaging, Cadbury said it would reduce packaging used per tonne of product by 10% across standard products and by 25% across more highly packaged seasonal items.

It also aims to use more environmentally sustainable forms of packaging - with a target of 80% being biodegradable.

The company has taken steps to reduce its impact on the environment, having switched its boiler house in Bournville from coal to gas and set up water- saving projects in water-scarce parts of the world such as Australia and Pakistan.

More initiatives will follow - including plans to encourage employees to behave in a more environmentally friendly manner.

Cadbury said the targeted reduction in its carbon emissions would be "absolute, not relative". "Even if the company grows to twice the size we will still be producing at least 50% less emissions than we do today," said CSR director Alex Cole.

However, the company said it would not adopt the Carbon Trust's trial carbon footprint label. "It definitely has value but whether consumers are ready for it to be in the form of a label, I'm not sure," said Cole.

However, PepsiCo this week revealed it would extend the use of the label to all varieties in its standard Walkers crisps range, in addition to cheese & onion.

It has also pledged to use only 100% British potatoes for the Walkers brand as part a move to reduce its carbon footprint.

The company currently sources about 90% of its potatoes from Britain, with the remainder coming from Belgium and Northern France. From 9 July all its standard crisps will be made with British-farmed potatoes.

"Our consumer research tells us people are increasingly concerned about the origin of their food and welcome our commitment to sourcing 100% British potatoes," said vice president of marketing Jon Goldstone.

Coca-Cola Enterprises, meanwhile, has announced the launch of a new lightweight 500ml bottle for its carbonates range, which will enable it to reduce the amount of PET packaging it uses by more than 700 tonnes a year.

Following trials partly funded by Wrap, CCE is to replace its 26g bottle with a 24g version for its Coca-Cola, Diet Coke, Coke Zero, Fanta, Sprite and Lilt brands.

Meanwhile, Associated British Foods has reached an agreement with BP and DuPont to build a £200m biofuel plant at Saltend, Hull. The plant will use wheat to produce 420 million litres of bioethanol a year.