LONDON (Reuters) – Britain’s competition regulator has blocked Sainsbury’s proposed 7.3 billion pound ($9.4 billion) takeover of Walmart owned Asda – a huge blow to the supermarket groups who wanted to combine to overtake market leader Tesco.

FILE PHOTO: Shopping bags from Asda and Sainsbury’s are seen in Manchester, Britain April 30, 2018. REUTERS/Phil Noble/illustration

The Competition and Markets Authority (CMA) said on Thursday that the deal would lead to increased prices in stores, online and at many petrol stations across the UK.

Sainsbury’s, Walmart and Asda said they had mutually agreed to terminate the transaction, opting not to challenge the CMA’s ruling through the Competition Appeal Tribunal, a specialist judicial body, which could have thrown it back to the CMA.

Sainsbury’s and Asda agreed the