London restaurants that don't source produce locally and ethically risk being "left behind", according to a report by sustainable food organisation London Food Link (LFL).
Three quarters of London diners want to see local foods named on restaurant and café menus, LFL's One Planet Dining report states.
Customers are particularly keen to vegetables, meat and poultry locally sourced.
The report recommends that restaurants and cafés in London train staff in how to find, buy, and cook local and seasonal foods, co-ordinate with suppliers and conduct environment audits to improve the sustainability of their food supply.
London Food Link, a division of food and farming charity Sustain is also calling for the industry to develop a "Local to London" brand and establish a green restaurant association.
Ben Reynolds, co-ordinator of London Food Link, said: "We rarely came across examples of restaurants or suppliers that had been offered professional support to promote sustainability."