Graham Simmonds, co-founder of Green Rewards, said: 'Our scheme comes purely from an environmental ethos, whereas this (CarbonCreditz) has been drummed up from a marketing perspective.'
Simmonds stressed that Green Rewards, which launched in June, was backed by leading figures from the environmental movement who vet companies and bar what they consider unethical brands. He added that with offsetting programmes there is a danger that consumers assume that their job is done and that they doesn't have to change their behaviour in terms of consumption.
Dave Evans, Chairman & CEO at Grass Roots, the group behind CarbonCreditz responded: 'I have made it a principle never to criticise competitors, especially new entrants. Markets grow precisely because there are new entrants, because someone has a slightly different view.'
Carboncreditz allows shoppers at affiliate stores to earn credits as they make purchases, which are then invested into carbon offset projects (1 creditz = 1p).
More than 1,000 affiliate retailers and brands have signed up to the scheme, including John Lewis.
The scheme will be promoted through a range of marketing activity including in-store, on pack as well as press advertising.
Consumers are able to set up an online account where creditz can be first stored and spent. However rather than just limiting individuals to offset projects, they can also be exchanged for energy saving products including energy efficient light bulbs and even A+ rated washing machines and refrigerators.