UPDATE 1-CSX CEO Harrison dies days after medical leave announced

(Adds chairman's statement, information about recent market performance)

NEW YORK, Dec 16 (Reuters) - CSX Corp Chief Executive Hunter Harrison has died, the freight railway operator said on Saturday, just a few days after announcing that he was taking a medical leave of absence.

Harrison, 73, died "due to unexpectedly severe complications from a recent illness," the company said in a statement on Saturday, adding that he would be succeeded for now by acting CEO Jim Foote.

Harrison, hired as CEO in March at the urging of activist investor Paul Hilal, had been in the midst of an ambitious and sometimes controversial effort to overhaul CSX by laying off employees and streamlining operations.

"The board will continue to consider in a deliberative way how best to maximize CSX's performance over the long term," CSX Chairman Edward Kelly said in a statement that called Harrison a "larger-than-life figure."

News of Harrison's leave of absence, announced late on Thursday, sent the No. 3 U.S. railway's shares tumbling as much as 10 percent on Friday. (Reporting by Christian Plumb, editing by G Crosse)