LONDON — Britain’s competition regulator said Friday it had begun an investigation into an $575 million investment led by Amazon in the London-based food-delivery service Deliveroo, the latest effort by a government to potentially check the reach of a technology giant.

In an order, the country’s Competition and Markets Authority said it had reasonable grounds to suspect that Amazon and Deliveroo had “ceased to be distinct” businesses or that they would essentially merge if the investment were to go through.

Work on the investment was ordered to halt pending the regulator’s inquiry into whether it posed competition concerns.

The order is the latest is a series of moves by governments worldwide to potentially curb the power of technology titans.

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U.S. regulators and lawmakers are studying whether Amazon, Facebook, Google and Apple have broken antitrust laws. And their European counterparts, long considered more active in enforcing competition rules, have been stepping up scrutiny as well.

The British competition authority announced earlier this week that it planned to take a closer look at technology companies, particularly online platforms.

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“It is our job to ensure that companies innovate and compete,” Andrew Tyrie, the regulator’s chairman, said in a statement. “And every bit as much, it’s our job to ensure that consumers are protected from detriment.”

Now one of those targets of scrutiny is Deliveroo, one of the top international companies in the business of delivering restaurant meals.

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Amazon announced in May that it would lead a $575 million investment round in the 6-year-old company, whose couriers are a familiar sight in European cities like London and Paris. (Existing Deliveroo investors, including the mutual-fund giants T. Rowe Price and Fidelity, were also part of the investment.)

The inquiry is notable because Amazon would own only a minority stake in Deliveroo. And the U.S. technology company does not currently run any restaurant-delivery service, having closed down its offering in Britain in December and its American one last month.

But speculation has swirled within the technology world for months that Amazon was interested in buying the startup outright.

A spokesman for Deliveroo said the two companies “have been working closely with regulators” to gain approval for the investment.