INM said it had received unsolicited approaches for its stake in APN, owner of the New Zealand Herald newspaper.
APN is also the biggest radio and outdoor advertising operator in Australasia. In New Zealand, it owns 50 percent of the biggest radio group, the Radio Network.
It also owns The Listener magazine and regional newspapers, including Hawke's Bay Today, the Bay of Plenty Times, The Daily Post at Rotorua, and the Wanganui Chronicle.
APN is also part of the co-operative which owns the New Zealand Press Association.
The Sydney Morning Herald (SMH) reported today that Kerry Stokes' Seven Network was believed to be considering using its $A1.2 billion ($NZ1.4 billion) in spare cash to expand into radio and outdoor advertising.
Market sources were saying Seven had been working with Macquarie Group investment bankers in the past few weeks seeking to put together a consortium.
The sources said the pair had been approaching other possible bidders who would take on APN's newspapers in Australia and New Zealand.
Seven declined to talk about its intentions.
West Australian Newspapers, whose biggest shareholder is Seven, was seen as possible buyer of APN's newspaper assets.
SMH, a Fairfax Media newspaper, said Fairfax was believed not to be interested in APN, having about $A500m in cash and undrawn credit facilities and not wanting to take on further debt in uncertain economic times.
But another Fairfax newspaper, The Dominion Post, said Fairfax might be interested.
Depending on how the Commerce Commission defined competition issues in the New Zealand media market, a possible scenario was that Fairfax might look to buy The New Zealand Herald as it did not have a daily newspaper in Auckland.
Fairfax, which did not own any New Zealand radio assets, might also be interested in the 50 percent stake in the Radio Network.
Fairfax New Zealand chief executive Joan Withers said it was unclear how the commission would treat applications from Fairfax and other companies with New Zealand media assets interested in buying all or some of APN's New Zealand assets.
"To date, the Commerce Commission has defined the New Zealand media market in terms of discrete media markets, rather than nationally," Ms Withers said.
SMH said any deal was far from certain. INM was believed to have put an initial price tag of $A4 a share on its stake -- a 66 percent premium on APN's closing price before the review was announced -- arguing the stock was oversold.
Analysts said INM would struggle to find a buyer willing to meet that price during the credit crunch and with APN's unclear profit outlook amid a looming advertising recession.
Anyone who buys more than 19.9 percent of a company also has to bid for the remainder.
