Two companies thought to be ready to fund a management buy-out of Trinity Mirror’s midland titles have received an opening salvo from the National Union of Journalists.

The union has made public a letter to private equity firms Barclays Equity and Exponent, warning them against "savage cost cuts" which it fears could be imposed to recoup some of the estimated £190m purchase price of the company.

The Birmingham Post & Mail, Coventry Newspapers and Midland Weekly Media could be sold off in time for Trinity’s financial results announcement due on August 2.

The union fears the Birmingham Mail may be turned into an overnight production operation instead of the current "live", same-day publication.

The letter released to the media supports what is happening to the paper under editor Steve Dyson's stewardship, saying: "The union believes this would put at risk the successful drive under the current editor to restore the paper’s valued reputation for live, breaking news which is helping turn around its sales. This strategy is supported 100 per cent by its staff, all of whom signed an NUJ petition in favour of keeping the Mail an evening newspaper.

"From the start of the process initiated by Trinity Mirror, we have maintained that any prospective purchaser of these widely respected newspaper titles and associated interests, must publicly commit to maintaining journalistic quality, integrity and credibility.

"This is something not just demanded by the NUJ, but also the wider community in which the titles circulate."

Progress under Steve Dyson includes publishing detailed local editions which are now recognised by readers as containing valuable news for them, and several major and popular campaigns have been launched.

The editor said in his own blog earlier this month: "This initial announcement [of the proposed sale] came in November last year, and the final stages are now being processed.

"This could see a formal change of ownership by September, and will result in a pretty instant property move and revealing of very modern publishing and multi-media plans.

"Instead of being owned by a large plc with ultimate bosses in London, the paper will probably be owned by locally-based investors.

"News on the eventual sale, IDs of new owners and location of new property will all come out in the autumn."

Chris Morley, NUJ North & Midlands regional organiser, said: "Nobody at the Post & Mail will shed a tear over the exit of Trinity Mirror. But we don’t want our members to be pitched into an even more extreme cost-cutting regime which will damage their hard-fought reputation for journalistic quality and credibility."