The Federal Trade Commission has questions for Amazon concerning the company's acquisition of iRobot for $1.7 billion.
It is the latest deal by the e-commerce giant coming under scrutiny by regulators amid growing concerns about the company’s market power.
On Tuesday, iRobot said both it and Amazon received a request for additional information in connection with an FTC review of the merger, according to a regulatory filing.
Both Amazon and iRobot said they would cooperate with the FTC’s review, which delays the completion of a deal.
The iRobot company is known for its popular Roomba vacuum cleaners.
Earlier this month, a group of some 20 pro-privacy and worker organizations, including Public Citizen and Fight for the Future, urged U.S. antitrust enforcers to stop the purchase.
The groups argued the deal would strengthen the already powerful position in smart home devices of the world's second-largest retailer.
The FTC also questioned Amazon's $3.9 billion purchase of primary health organization One Medical earlier this month.
The same concern about the company's expanding market power where raised.
iRobot and Amazon both declined to comment.
Following an investigation, the agency can challenge a merger in court, seek remedies or do nothing, which allows the deal to close.
The agency said it retains the right to challenge a deal even after it is closed.
The Associated Press contributed to this report.