A Waitrose initiative to turn food waste into electricity rather than send it to landfill is to be rolled out to a further 66 stores.

By May, more than half Waitrose's stores will be sending their food waste to be converted into energy through anaerobic digestion.

The retailer has already diverted 50% of its total operational waste away from landfill. It aims to divert 95% by 2013.

"Anaerobic digestion has proven to be a sustainable way of eliminating the need to send it to landfill," said recycling and waste manager Arthur Sayer.