The company was working on the IPO with Morgan Stanley and Nomura Holdings, the report said.

The app, popular in Japan and one of the world's largest with some 450 million users, could command a valuation of more than USD 10 billion, the sources were cited as saying.

Line has not yet decided on a stock exchange, the size of an IPO or which investment banks would underwrite the offering, Bloomberg said.

Naver and Line were not available for comment outside of Asian business hours. Officials at Morgan Stanley and Nomura were not immediately available for comment.

Investor interest in mobile messaging apps has grown in the wake of Facebook's record USD 19 billion acquisition of WhatsApp, which pushed up industry valuations and cast a spotlight on the rapidly expanding market.