Fears have been raised about the effect a proposed merger of NZME and Fairfax could have on New Zealand's media.
"We have two major print media networks which are competing against each other, which is always good, and two massively popular websites, of the Herald and Stuff, competing against each other, Labour commerce spokesman David Shearer said today.
"I can't see any good coming out of merging this so that we have effectively one newspaper network for the entire country."
APN News and Media and Fairfax Media are in "exclusive talks" to fold their New Zealand operations - NZME and Fairfax NZ - into a major listed New Zealand media company.
The new company would bring two New Zealand major publishing empires together, and is subject to shareholder and regulatory approvals, including the Commerce Commission.
Mr Shearer said a merger would negatively affect media freedom in New Zealand.
"It puts an enormous amount of power in the Fourth Estate into the hands of very few people and I hope the Commerce Commission sees it that way.
"Going on past records, I'm not that confident.''
Green Party MP Gareth Hughes said the proposed merger was bad news for a broad media environment and showed there was a need for regulation to oversee media ownership issues.
Mr Hughes said a diverse and competitive media environment was important for democracy and the Commerce Commission was not allowed to consider issues such as the unique role of media companies.
"Many other countries have specific rules that prevent media monopolies from forming, but New Zealand doesn't. I think it's unlikely these Australian-owned media companies would even dream of proposing a virtual monopoly over newspapers in their home country, under current rules there.''
He said countries such as Australia and the United Kingdom had criteria to oversee ownership rules, digital convergence issues, and local content quotas through Australia's ACMA and UK's OfCom.
"The people who lose out from a newspaper merger will be the journalists whose jobs are cut and citizens who want a choice about where they get their news from.
Broadcasting Minister Amy Adams said it was not for her to comment on the merits of mergers between private companies.
But she suggested that the Government would not stand in the way of a merger between NZME and Fairfax.
"Ultimately it's for the Commerce Commission to decide on competition issues."
Ms Adams said "convergence" was having a "dramatic impact" on the telecommunications, media and entertainment sectors.
"New Zealanders want to access their content in different ways and on multiple platforms, and businesses across these sectors face a number of challenges as they adapt," she said.
"The distinctions between print, radio, television and online news are fading. Generally, digital convergence is giving New Zealanders greater access to content than ever before.
"Through platform convergence, previously distinct media platforms compete with each other at a level much greater than ever before - with television companies publishing editorials, for example, or newspaper websites running video clips."