SYDNEY, Australia — The Australian media group Nine Entertainment announced a takeover on Thursday of Fairfax Media, publisher of some of the most powerful voices in Australia’s news industry, in a bid to create a media giant encompassing print, television and digital assets.

Critics of the deal immediately raised concerns about concentration of media ownership in Australia and the future editorial independence of Fairfax’s prominent publications, which include The Sydney Morning Herald and The Age. The combined business would include Nine’s free-to-air television network and Fairfax’s print and online publications, like The Australian Financial Review and a lucrative online real estate portal, Domain.

“We are confident that the strength of the combined management team and staff will ensure the continuation of our quality journalism,” Greg Hywood, Fairfax’s chief executive, said in a joint statement announcing the merger.

Mr. Hywood is expected to leave Fairfax in about six months. The combined company would be called Nine, and Nine’s current shareholders would own a majority of the new business. The deal, estimated to be worth 4 billion Australian dollars, or roughly $3 billion, is expected to be completed by the end of the year.