Asda has clung on to the title of cheapest retailer by the skin of a sun-dried tomato to secure a sixth straight week at the top of the charts. 

Despite offering unbeatable prices on seven items, Asda found itself in the unusual position of being most costly on two products - Nestlé Shreddies and Branston Pickle. But a £1.20 reduction on sun-dried tomatoes enabled it to hold off the challenge of a resurgent Sainsbury's by a mere 57p.

As Asda's prices fluctuated, Sainsbury's remained steady with just three price reductions and one increase.

It joined the other retailers in upping the price of broccoli, but its hike was the smallest at 30p compared with an average of 44p.

At 99p, Sainsbury's new potatoes were the only ones under a pound, while the Old El Paso Fajita Dinner Kit at £1.76 was a full 79p cheaper than at any of its competitors.

Morrisons trumped its peers on three items, most notably Birds Eye Simply Cod in Batter, which at £2.95 was 65p cheaper than at its rivals. At £2.49, Morrisons' own-label sun-dried tomatoes were almost double the price of Asda's, while a hefty 95p increase on the unsmoked gammon joint was the difference between a second and third-placed finish.

Tesco surrendered last week's second place after providing only one item - Nestlé Shreddies - cheaper than its rivals. Price increases on gammon, Cathedral City Mature Cheddar and broccoli meant its £55.51 basket was almost £2 more expensive than Asda's.

Waitrose enjoyed a rare success by delivering more lowest priced items than either Tesco, Sainsbury's or Morrisons. Its Hovis square cut white bread, fresh semi-skimmed milk and own-label vegetable oil all undercut rivals' prices, proving Waitrose can still compete effectively on household staples.

But at £61.70, the basket of goods still checked out more than £5 pricier than fourth-placed Tesco, let down by hefty differentials on its gammon, Smirnoff Ice and Birds Eye cod.