The National Union of Journalists has already made clear it will be raising concerns over media plurality with business secretary Lord Mandelson in the wake of today's £44.8m purchase by Trinity Mirror.

The union believes the proposed deal raises issues of editorial independence as well as "diversity of information and media" in the North-West.

One former Trinity daily editor has already predicted the sale will lead to consolidation elsewhere in the regional press industry - a prospect which the NUJ views with horror.

Deputy general secretary Michelle Stanistreet said: "The move by Trinity Mirror has implications for the future ownership of local media across the UK, as major publishers weigh their chances of swallowing up what remains of independent publishing in Britain.

"The concerns for diversity of information and media in the North West are an immediate issue which we will be raising with the Department of Business, Innovation and Skills.

"Trinity Mirror already publishes the Liverpool Post and Echo titles, in addition to a substantial stable of weekly papers across Cheshire and Merseyside. Now it will also control the prestigious Manchester Evening News, which has a series of titles in the region.

"This all raises issues of editorial independence which should be of concern to government and community leaders as well as the media industry."

All eyes will now be on the government to see how, if at all, it responds to the union's concerns.

Were it to block the deal, or refer it to the Competition Commission, it would risk GMG deciding to close the MEN altogether, as Guardian media writer Steve Busfield hinted in a blog post today.

Commenting on today's deal he wrote: "There will, inevitably, be cost-cutting, but, for the sake of the business, that has got to be better than closure....GMG clearly did not want to close the MEN, but, without the sale, it might have had no option."

If however the govermment waves the deal through, it will be seen as giving the green light to other possible mergers and asset-swaps between publishers with interests in geographically contiguous areas.

Former Birmingham Post editor Marc Reeves, writing on the BusinessDesk.com's West Midlands portal which he edits, predicted the sale would herald just such an outcome.

He said: "My money is on a rise in the number of deals amongst the major publishers following the TM-GMG shuffle, as more try to optimise the geographical 'sense' of their sometimes disparate and accidental portfolios."