Which? compared the cost of 42 popular grocery items at convenience chains Morrisons Daily, Sainsbury's Local and Tesco Express against prices at their full-sized supermarkets.

An investigation has found that Tesco, Morrisons and Sainsbury's all charged more for a basket of shopping in their smaller local convenience stores.

Morrisons says it will roll out its discount More Card loyalty scheme to its convenience stores “in the coming months” after the Yorkshire company was criticised for higher prices in its smaller shops compared to its supermarkets.

In total, the basket of 42 groceries would have averaged around £11 more at Sainsbury’s Local and £10 more at Tesco Express for loyalty scheme members, compared to their price

The consumer champion compared the cost of 42 grocery items at convenience chains Morrisons Daily, ­ Sainsbury's Local and Tesco Express against prices at their full-size supermarkets. The biggest different was at Morrisons Daily,