Barnes & Noble Inc unveiled a new e-reader on Tuesday that is the size of a paperback book and has a battery life of two months, features designed to help it compete with Inc and Apple Inc.

Barnes & Noble's introduction of a new Nook comes just days after John Malone's Liberty Media Corp offered to buy the bookstore chain for $1 billion. A source familiar with Liberty Media's thinking has said that one of the driving forces in the takeover bid is Liberty's desire to acquire the Nook franchise.

Barnes & Noble, which introduced its first e-reader in 2009, has been trying to remake itself into a digital bookseller to cope with readers' shift away from print books.

The latest Nook will sell for $139 and start shipping on June 10. It weighs 7.5 ounces and has a 6-inch display.

(Reporting by Liana B. Baker and Phil Wahba, editing by Gerald E. McCormick)