Amazon and Deliveroo had not cleared the doubts raised earlier this month regarding the stake acquisition Britain’s competition regulator has decided to deepen its investigation into Amazon.com Inc’s purchase of a stake in online food delivery group Deliveroo, a move that could delay the closure of the deal. The Competition and Markets Authority (CMA), which launched a probe in June, on Friday moved to “Phase 2” of the investigation as both Amazon and Deliveroo did not offer remedies to its concerns before a Dec. 18 deadline, the regulator said. Amazon led a $575 million fundraising in Deliveroo in May and the probe is likely to put at risk the e-commerce giant’s efforts to compete with Uber Eats, Just Eat and Takeaway.com in food delivery. Earlier this month, the CMA had found that Amazon’s investment into Deliveroo in its current form could harm competition in restaurant food delivery and online convenience grocery delivery. Both Deliveroo and Amazon had defended the deal after the initial probe and the Seattle-based company had said the funding would “lead to more pro-consumer innovation.” Deliveroo on Friday said it was working with the CMA and said the deal would “add to competition, helping restaurants to grow their businesses, creating more work for riders and increasing choice for customers.” Amazon did not immediately respond to a request for comment.