May 28 (Reuters) - Scott Sheffield, the former CEO of Pioneer Natural Resources, has requested the US Federal Trade Commission to vacate its order that barred his inclusion on Exxon Mobil's board.

Sheffield also sought the dismissal of the proceeding without further action, according to a comment filed by his legal counsel before the regulator on Tuesday.

The U.S. antitrust regulator had given its go-ahead to Exxon's $60 billion purchase of Pioneer earlier in May, but barred Sheffield from Exxon's board on allegations that he attempted to collude with the Organization of the Petroleum Exporting Countries (OPEC) to raise oil prices.

"In straining to find a reason to criticize the merger of Exxon and Pioneer, the FTC stepped well beyond its proper mandate and unjustly smeared Sheffield," according to the counsel's comment.

FTC did not immediately respond to a Reuters request for comment. (Reporting by Sourasis Bose in Bengaluru; Editing by Shailesh Kuber)