ATTEMPTS by Amazon to buy a minority stake in an online food delivery business have been thrown into doubt by the competition watchdog.

The Competition and Markets Authority (CMA), which has been investigating the deal since it was first announced in May, said it had serious concerns that competition could be stifled.

The watchdog said it could launch full-scale investigation into the deal.

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Andrea Gomes da Silva, executive director at the CMA, said: “There’s a real risk that it could leave customers, restaurants and grocers facing higher prices and lower quality services ... because the significant competition which could otherwise exist between Amazon and Deliveroo would be reduced.”

Concerns include discouraging Amazon from re-entering the restaurant food delivery sector – having launched and closed its Amazon Restaurants business a year ago.

An Amazon spokesman said: “Amazon believes that this investment funding will lead to more pro-consumer innovation by helping Deliveroo continue to build its world-class service and remain competitive in the restaurant food delivery space by creating more highly-skilled jobs, innovating in the restaurant food delivery sector, and developing new products for customers.”