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(Reuters) - The U.S. Federal Trade Commission (FTC) has requested for more information from AbbVie Inc ABBV.N and botox maker Allergan Plc AGN.N on their $63 billion deal, the companies said on Friday.

AbbVie and Allergan said they still expect the deal to close in early 2020, and were cooperating with the antitrust regulator.

The scrutiny into the deal, which combines two of the world’s biggest pharmaceutical companies, follows a request by a dozen advocacy groups and unions to the FTC to block the purchase.

In a letter seen by Reuters, the groups noted that the deal would create the fourth largest pharmaceutical company at a time when rising drug prices have become a hot political issue.

AbbVie said the FTC’s second request for information was expected.

The deal to buy Allergan, announced in June, came as Abbvie faced pressure to diversify its portfolio, and as its blockbuster drug Humira, the world’s best selling medicine, faces competition from cheaper versions.