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WASHINGTON (Reuters) - In an unusual move on Thursday, a federal judge raised the prospect of not approving CVS Health Corp’s deal to buy insurer Aetna Inc, which closed earlier this week, during a routine portion of the legal process.

Judge Richard Leon of the U.S. District Court for the District of Columbia objected to what he said was the government’s and companies’ treatment of him as a “rubber stamp” for the deal, noting that CVS had closed its deal to buy Aetna for $69 billion on Wednesday.

CVS said in a statement, “It’s commonplace for acquisitions to close before this final step in the process is complete, and our focus remains on delivering on the combined company’s potential.”

The Justice Department did not immediately return a request for comment.

The Justice Department gave its OK in October for the merger of CVS, a pharmacy and benefits manager firm, and Aetna on condition that the health insurer sell its Medicare Part D drug plan business to WellCare Health Plans. The court must approve the agreement between the government and merging companies.

Leon raised the prospect of not deciding on the deal until the summer, or perhaps rejecting it, before setting another hearing for Monday.

“I was reviewing your motion, which, of course is not opposed. And I kind of got this uneasy feeling that I was being kept in the dark, kind of like a mushroom,” Leon told lawyers for the Justice Department and the two companies, noting that the American Medical Association, among others, had objected to the deal.

“I’m very concerned, very concerned that you all are proceeding on a rubber-stamp approach to this,” he told them, according to a transcript of the hearing.

(This story corrects attribution in paragraph 3 to reflect merged companies)