WASHINGTON (Reuters) - A U.S. Democratic senator on Friday questioned the Federal Trade Commission’s quick approval of Amazon.com Inc’s purchase of Whole Foods Market Inc this week, less than three months after the $13.7 billion deal was announced.

FILE PHOTO: Senator Amy Klobuchar (D-MN) questions Supreme Court nominee judge Neil Gorsuch during his Senate Judiciary Committee confirmation hearing on Capitol Hill in Washington March 21, 2017. REUTERS/Joshua Roberts

The FTC said on Wednesday that it had ended its antitrust investigation without seeking a second request for additional information on a deal that has sent shock waves through the grocery industry.

Senator Amy Klobuchar of Minnesota said in a statement on Friday that she was concerned about the FTC’s decision to “not fully review” the deal, which was announced on June 16.

“Amazon’s increased access to data on consumers and their behavior, and its dominance in internet retail sales, raises questions about whether this merger harms consumers and suppresses competition,” she said.

Klobuchar said she would ask the FTC to explain why it made such a quick decision.

Seattle-based Amazon declined to comment. The FTC did not immediately reply to a request for comment.

After getting the approval of the FTC and Whole Foods shareholders this week, Amazon said on Thursday that it planned to complete the acquisition on Monday and simultaneously introduce lower prices on some grocery staples.

The world’s biggest online retailer also said it planned to start selling some Whole Foods-branded products on its website and offer incentives to its Prime members at Whole Foods stores.

Shares of major grocery stores fell sharply on Thursday on fears that Amazon’s move would spark a new round of price wars in the industry, but they recovered somewhat on Friday.

The approval was one of the first major decisions by the Trump administration’s FTC. The commission has five seats but just two members at present, and Trump has not yet nominated anyone to fill the remaining three positions.

Earlier this month, Reuters reported that President Donald Trump’s leading choice to run the agency was Washington lawyer Joseph Simons, who was a top FTC official under President George W. Bush.

A partner at law firm Paul, Weiss, Rifkind, Wharton and Garrison LLP, Simons would replace acting Chairman Maureen Ohlhausen, who has been running the FTC since January.

The U.S. Senate still has not approved Makan Delrahim, Trump’s choice to head the Justice Department’s antitrust division.

Congressional Democrats in July proposed taking a harder line on mergers and strengthening antitrust laws to give regulators more tools to block such deals or revisit those that were previously approved. “Growing corporate influence and consolidation has led to reductions in competition, choice for consumers, and bargaining power for workers,” as well as higher prices, they said.

The Trump administration is reviewing a number of mergers, including AT&T’s Inc proposed $85.4 billion purchase of Time Warner Inc, the owner of HBO, Warner Bros and news network CNN. The Justice Department and AT&T have been discussing potential conditions in recent weeks.