LONDON (AP) — British competition regulators have blocked J. Sainsbury Plc's 7.3 billion-pound ($9.4 billion) purchase of Walmart's Asda unit, which would have created the U.K.'s biggest supermarket chain.

The Competition and Markets Authority says the deal would have increased prices and reduced the quality and range of products available to shoppers.

Stuart McIntosh, who led the agency's review of the deal, said Thursday that "we have concluded that there is no effective way of addressing our concerns, other than to block the merger."

Sainsbury announced plans to buy Asda last year as it sought to cut costs amid competition from discount chains that have increased their share of the U.K. grocery market. Walmart is pulling back from its international operations as it faces challenges in exporting its low-price strategy to foreign markets.