The Competition and Markets Authority (CMA) is to ramp up an investigation into heightened food prices in supermarkets and retailers.

The watchdog said it had been working to understand how well markets in essential goods and services were working. The CMA has identified road fuel and groceries as a priority and was analysing food pricing practices online and in shops.

While global factors had been a main driver of grocery price increases, the watchdog said it was 'important to be sure that weak competition is not adding to the problem.'

The CMA said: "We are announcing the stepping up of our work to understand whether any failure in competition is contributing to grocery prices being higher than they would be in a well-functioning market.

"First, completing work to assess how competition is working overall in the grocery retail market, drawing on publicly available data and other information. Second, in parallel, identifying which product categories, if any, might merit closer examination across the supply chain."

It said it would engage with a wide range of industry participants, experts, and other stakeholder groups to inform its assessment, adding that it would provide an update on this work over the coming months.

Sarah Cardell, its chief executive, said the rising cost of living was putting people and businesses under sustained financial pressure. "The CMA is determined to do what it can to ensure competition helps contain these pressures as much as possible," she explained.

"We recognise that global factors are behind many of the grocery price increases, and we have seen no evidence at this stage of specific competition problems. But, given ongoing concerns about high prices, we are stepping up our work in the grocery sector to help ensure competition is working well and people can exercise choice with confidence."