A list of 29 household items were bought in a Tesco store last November for the purposes of comparing prices following the removal of the Groceries Order, nine weeks ago. When the same items were bought in Tesco last week, 10 had increased in price, and 17 had been unaffected by the change. Only two items had decreased in price.

Barry's Tea Bags had increased by 11%, from 2.69 to 2.89, while Avonmore Slimline Milk had gone up by 7%, from 93c to 97c. One of the biggest increases was in Gillette Sensor Excel Razor Blades, which had gone up by 30c, from 7.99 to 8.29. This was closely followed by a 29c increase in the price of Amoy Stir Fry Sauce, and a 20c increase in Sellotape.

There was a 9% increase in the cost of Ready Brek, which went from 2.77 to 2.95, while a box of Anadin tablets now costs 12c more than it did last November. Just Bouillon stock cubes and Just Bouillon beef stock had both increased by 6c and 7c respectively.

According to financial expert Eddie Hobbs, these price increases cannot be explained by a rise in inflation. "In the overall scheme of things, grocery price inflation has been quite modest at about 1%, " he said. "Anything more than that is a clear price increase."

Following widespread national debate, the Groceries Order was finally abolished on 20 March last, meaning supermarkets are no longer prohibited from selling packaged groceries below cost.

Critics of the Groceries Order were adamant that its removal would result in much greater competition between supermarkets, and thus lower prices for the consumer.

However, the majority of items bought by a Sunday Tribune reporter in Tesco last week appeared to have been unaffected by the abolition of the order, with staple shopping-basket items such as Kerrygold butter, sugar, Domestos, frozen peas, full-fat milk, cheddar cheese, cooked ham, and Dairygold spread all remaining at the same price.

Only two items had fallen in price.

Tesco's own brand guacamole dip had gone from 2.29 to 1.79, and Tesco's 2.5kg Roosters Potatoes had been reduced from 3.69 to 2.49. However, the price of potatoes fluctuates greatly from season to season, and such a reduction may be a reflection of this.

A spokeswoman for Tesco said the price increases found by the Sunday Tribune may have been a result of increases imposed by suppliers. "We will be resisting supplier increases from now on and we will be working to deliver the best possible prices to our customers, " she said.

Then, on Friday, Tesco announced its intention "to reduce the prices of all products previously controlled by the Groceries Order" over the coming months. The move followed a customer email blitz on Tesco and Dunnes Stores, led by Hobbs, who had claimed that both chains were failing to pass on discounts they were getting from suppliers since the abolition of the Groceries Order.

Friday's pledge by Tesco to cut prices on around 5,000 products is expected to spark a price war between supermarkets.