Express supermarket stores are charging three times as much as their larger counterparts, investigation finds

Express supermarkets are charging customers up to three times more for their groceries than superstores from the same chain, an investigation has found.

Some fruit and vegetables have a mark up of up to 177 per cent as smaller shops charge more for the same product.

Branded items do not have consistent prices across stores from the same chain either, according to the investigation by the BBC.

The analysis found that a Tesco Express store sold a banana for 25p, while the local superstore sold it at a fraction of the price for 9p.

Similarly at Marks and Spencer, a banana costs 40p in the convenience store and 18p in the big shop.

Mr Kipling's French Fancies cost £1.95 in a Sainsbury's convenience store, and £1.60 in the supermarket.

The BBC visited a variety of shops between September and October this year to compare prices.

At Sainsbury's and Marks and Spencer stores in Birmingham, and Waitrose shops in Shropshire, 45 of 50 items cost more in the convenience location, while at the Tesco Express, 39 of 50 items cost more than in the superstore.

The shops all said the mark-ups were due to smaller shops facing higher operating costs, including higher rents and increased rates for longer opening hours.

Sylvia Rook - Lead officer, Chartered Trading Standards Institute, told the BBC: "With normal economy and supplier demand, it is often the case that smaller shops, and those in more remote areas, will charge more.

"I always think that when you look at service station petrol prices on motorways, that is very telling, because they are normally hugely more expensive but they are open 24 hours and have higher overheads.

"With smaller stores, deliveries are also harder to get to them."