UPDATE 1-Barnes & Noble chairman to bid for company's retail assets

* Riggio says deal would exclude Nook business

* Deal would be mainly cash with assumption of some debt

* Riggio already owns nearly 30 pct of company

* Shares rise 25 percent before the bell

Feb 25 (Reuters) - Barnes & Noble Inc Chairman Leonard Riggio has told the board he plans to buy the retail assets of the company including Barnes & Noble Booksellers Inc and barnesandnoble.com, but excluding the Nook digital reader business, sending the company's shares up 25 percent before the bell.

The purchase price is expected to comprise mainly cash and include the assumption of certain debt, Riggio, who owns nearly 30 percent of Barnes & Noble, said in a regulatory filing on Monday. ())

Barnes & Noble shares closed at $13.51 on the New York Stock Exchange on Friday, valuing the company at about $809 million.

Riggio said he would provide the equity financing and arrange any debt financing for the deal.

Riggio, the company's largest shareholder, pioneered the book superstore format in the 1980s and 1990s.

The Wall Street Journal reported the planned deal on Sunday.