Online retailer Amazon.com Inc said on Thursday it will exclusively publish digital editions of 20 classic books owned by the Wylie Agency, including authors such as Philip Roth, John Updike and Norman Mailer, for the first time on its Kindle electronic reader.

Amazon's move is a sign of intensifying competition in the crowded digital book format, including Apple Inc's iPad and Barnes & Noble Inc's Nook e-reader.

The Wylie deal may set off a race among the makers of electronic readers to buy digital rights to classic books that will help them to win more customers.

This is the first time books like Philip Roth's Portnoy's Complaint and Ficciones by late Argentine writer Jorge Luis Borges will be available electronically, Amazon said. All of the books are exclusive to the Kindle Store for two years.

Kindle customers can download these books for $9.99.

(Reporting by Sakthi Prasad in Bangalore; Editing by Derek Caney)

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