Revealed: Why prices are rising faster in rip-off UK

British consumers are suffering the biggest increases in food prices and energy bills of any major economy, figures showed yesterday.

The cost of filling a supermarket trolley rose by 6 per cent in April compared with the same month last year - nearly twice the EU average.

Among the 30 members of the Organisation for Economic Cooperation and Development only Turkey, Hungary and Mexico saw larger gains in grocery prices last month.

The OECD also revealed that utility prices are rising more here than overseas - even after recent cuts in bills by firms such as British Gas and Powergen.

They increased by 7.9 per cent in April compared with the same month last year.

The OECD figures will re-ignite accusations that British supermarkets are using their market dominance to rip-off customers.

Tesco and Asda have claimed that poor harvests and rising raw material costs are forcing them to jack up some prices. But critics say this is a worldwide problem, making it difficult to explain why UK customers are suffering more than most.

Shoppers in countries including the U.S., Germany, France and Italy are all seeing substantially lower rates of food price inflation, the OECD said.

A report last month by Royal Bank of Scotland entitled The Return of Rip-off Britain? said there may be a "sinister explanation" for the discrepancy between price gains here and abroad.

It argued that supermarkets may be finding it easier to "exploit their monopoly position and raise prices".

The cost of vegetables has surged 15 per cent in Britain in the past year, while fish prices are up 12 per cent.

These gains have pushed the UK towards the top of the world inflation league, adding to pressure on the Bank of England for further interest rate increases.

Although the Consumer Prices Index, which measures annual inflation, slipped to 2.8 per cent in April from 3.1 per cent in March, that is still higher than any other major OECD economy.

Shane Brennan, of the Association of Convenience Stores, which represents 32,000 small shops, said the research highlights the need for increased competition in the retail sector.

"The dominance of the major supermarkets creates real problems for consumers, and these statistics suggest that this is now playing out in food price inflation," he said.

"Four companies control 75 per cent of grocery sales in the UK."

The Competition Commission is conducting an inquiry into whether UK food shopping is too concentrated in the hands of a few powerful players.

Malcolm Pinkerton, of the British Retail Consortium, said the rapid gains in UK prices may partly be related to the popularity of costly organic products.

"Overall food prices are much lower than they were ten or 15 years ago," he said.

While British energy prices rose 7.9 per cent, the average annual increase across the OECD was 1.9 per cent.

In the euro area it was 0.4 per cent. Only households in Turkey and Hungary saw bigger increases.

Shortfalls in gas imports last winter led to painful price rises for British families. Since then wholesale prices have fallen sharply, prompting calls for UK energy giants to slash further the prices customers pay.

But some analysts say the brief spell of cuts in utility bills may already be coming to an end.