UPDATE 1-Integrys Energy to buy private utility for $440 mln

* To add 593 MW power plant in Wisconsin

* To close the deal around April 1, 2013

(Adds details, shares)

Oct 1 (Reuters) - Electric and natural gas utility Integrys Energy Group Inc will buy privately held Fox Energy Co LLC for $440 million to add a 593 megawatt power generating plant in Kaukauna, Wisconsin.

Integrys unit Wisconsin Public Service Corp will pay $390 million for the Fox Energy Center, expected to run primarily on natural gas, and $50 million for the early termination of an existing tolling agreement.

Fox Energy Co is owned by subsidiaries of GE Co and Tyr Energy Inc.

The transaction is expected to close around April 1, 2013, Chicago-based Integrys said in a statement.

Integrys shares, which have lost about 16 percent of their value over the last two months, closed at $52.20 on the New York Stock Exchange on Friday.

(Reporting by Sunayan Bhattacharjee in Bangalore; Editing by Don Sebastian)

((sunayan.bhattacharje@thomsonreuters.com, within U.S. +1 646223 8780, outside U.S. +91 80 4135 5800, Reuters Messaging: sunayan.bhattacharje.reuters.com@reuters.net))