Supermarket fridges should be closed, campaigners have said, as it emerges that the appliances use up one per cent of all UK electricity.

Most shops use open fridges, which use far more energy to stay cool than alternatives with doors. These are favoured by supermarkets because it means customers are able to grab products quickly.

However, they have been criticised by campaigners and MPs as a "massive waste of energy and money" which are contributing to global warming.

A study carried out with the support of the Department for Environment, Food and Rural Affairs found that "retail food outlets are responsible for around three per cent of total electrical energy consumption".

It added that "refrigeration systems account for between 30 per cent and 60 per cent of energy used."