(Reuters) - The U.S. Federal Trade Commission is set to decide whether to sue to block Exxon Mobil's ( XOM ) $60 billion acquisition of Pioneer Natural Resources ( PXD ) in the coming days, Bloomberg News reported on Wednesday, citing people familiar with the matter.

Exxon complied with FTC's second request for information at the beginning of April, triggering a 30-day period within which the antitrust agency must make a decision, the report added.

The timeline could be extended if regulators and Exxon agree to continue working on ironing out competition issues, the report said.

Exxon had said last week that the deal is expected to close in the second-quarter.

The FTC had sent a second request to both the companies last year. It had also sought additional information from Chevron and Hess as well as Endeavor and Diamondback Energy ( FANG ) related to their respective mergers.

Exxon and Pioneer did not immediately respond to Reuters requests for comment, while the FTC declined to comment.

Antitrust experts said in October that despite the size of the proposed Exxon-Pioneer deal, the FTC would struggle to stop it because it is a merger of producers rather than refiners or retail outlets.