Tesco chief executive Philip Clarke has warned that food prices are set to rise long-term as global demand mounts.

Clarke told the Observer: “Over the long run I think food prices and the proportion of income spent on food may well be going up. Because of growing demand it is going to change. It is the basic law of supply and demand.”

Clarke said in February that initiatives to increase the volume of British products sold in Tesco would not mean that food would become more expensive but he said that, while price is important, “it’s not everything – we’re working very hard with our buyers so they’re not just focused on price.”

The major grocers have historically pledged to keep food prices low amid rising commodity costs and demand for food increasing as the global population grows.

Clarke’s comments follow those of Waitrose managing director Mark Price, who has previously said food price inflation is inevitable.

Food price inflation rose from 2.4% in May to 2.7% in June, according to the Office for National Statistics.