Barnes & Noble unveiled a new Nook e-reader on Tuesday that weighs less than a paperback book and has a battery life of two months -- features designed to help it compete with Amazon.com and Apple.

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

The latest Nook will sell for $139 and start shipping on June 10. The touchscreen device weighs 7.5 ounces, has a 6-inch display, and allows a user to look up words, highlight passages and adjust the font size. It can store up to 1,000 books.

The new Nook lands in a highly competitive market, where the iPad and the Kindle are battling with Barnes & Noble for customers who want to read books on small portable devices.

Barnes & Noble executives trumpeted the new Nook's simplicity, saying designers streamlined it, reduced the number of buttons and armed it with a paper-like screen.

The is the most advanced e-reader on the market, chief executive William Lynch said on Tuesday.

The 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 has said that one of the driving forces in the takeover bid is Liberty's desire to acquire the Nook franchise.

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

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