The price of inexpensive everyday foods rose by 17% in the 12 months to September, Office for National Statistics (ONS) data showed, more than the average rate of food and drink inflation.

The figures, based on internet-sourced supermarket data for 30 everyday grocery items, showed cost of items already increased by 7% in the year to April.

Some commodities have increased by more than 17% for the year. Vegetable oil rose in price by 65%, pasta products by 60%, tea by 46%.

The growth of low-cost food products exceeds the overall rate food and beverage inflation which was published by the ONS last week. This indicator was 14.5%.

Some goods have really become cheaper.

The biggest drop in prices was recorded for fruit orange juice, which fell by 9%. Minced beef also became cheaper by 7%.

Announcing the data, the ONS warned that they were obtained using new, innovative methods and as a result are less reliable than official statistics.

For half of the 30 sample items looked at, the average lowest price at retailers increased faster than the latest available official figures for consumer price inflation for food and soft drinks, the ONS said.

But he added that caution should be exercised when comparing it to the official measure of food and drink inflation, as it contains many more items than the 30 used in this analysis and uses a different methodology.

For example, products may not always be available in-store or online as reflected in the collected data, so analysis may be sensitive to product availability and the specific products being substituted.