The price of oranges has risen this week by a whopping 61%. Hurricanes in the US and Caribbean have affected the volume of oranges produced there this year, while frost in South America and flooding in South Africa have also contributed to the downturn in yields, which has prompted this latest surge in price.

The cost of a single orange at Tesco, Sainsbury's and Somerfield has jumped by 11p over the past seven days and now stands at 29p.

But at Asda this week the price of an orange was at 18p although it is likely to rise by next week's report. Asda produced by far the cheapest basket this week ahead of Sainsbury's and Tesco and continued to carry the lowest price for a whole cucumber, and a four-pack of prepacked baking potatoes.

Meanwhile, with just 16 trading days left ahead of Christmas day, there has been a sharp rise in the number of special offers advertised this week. All six of the major multiples have taken out a spate of full-page advertisements in the national press, with Morrisons offering buy-two-get-two-free on a number of products.

Nine of the 33 items on this week's shopping list were on promotion at Asda, according to our shopper.

Some of the tempting deals included four for £2.50 on apple juice, and three for £2.50 on loaves of Hovis bread.

However, the price of a four-pack of Stella Artois has not shifted from £4.18 at the top four multiples in the past few weeks.

Seven of our 33 items were under offer at Morrisons this week, which at £40.28 provided the fourth-cheapest shopping basket on our list.

Second-placed Sainsbury's has been honing its price-cutting strategies over the past few weeks as it fights for its place as the UK's third-cheapest supermarket ahead of Morrisons, which has claimed The Grocer 33's cheapest basket three times in the past six months. However the true cost-cutting king will be revealed next week when we publish the results of The Grocer 33's latest six month review.