Trinity chief executive Simon Fox described the £220m deal, which will create the biggest regional newspaper publisher in the UK, as a “good day for local media.”
But the union says it is seeking assurances about what the £220m deal will mean for staff and existing newspaper titles.
Trinity has already said it will be looking to make savings of £10-12m as a result of “cost synergies” arising from the acquisition.
Martin Shipton, FoC of the Trinity Mirror group chapel, said: “Our primary concern is what this deal will mean for our members. The union will be seeking urgent assurances and clarifications over the ramifications of the take-over for staff and the continuation of existing titles.”
General secretary Michelle Stanistreet, left said: “This deal is a further blow to media plurality. Already there is little choice on offer in our cities and major towns when it comes to buying a local newspaper. Trinity Mirror’s domination will vastly reduce the little choice there is.
“The never-ending consolidation of the local media market is a consequence of the difficulties in increasing advertising revenue on digital products, but what is needed is a long-term vision and not short-term speculation.
“We are now in danger of having identikit newspapers across the UK. The promise of further cuts to editorial is also depressing, not just to the readers who will notice a drop in quality, but to all our members who care passionately about their work and getting out the best- possible newspaper.”
National organiser Laura Davison added: “Staff at Trinity Mirror and Local World will be looking for immediate reassurances about jobs and terms on the back of this announcement.
“Staff across the businesses will want to know that the company intends to invest in journalism to ensure future success and not simply adopt a narrow vision involving cuts more in the interest of shareholders than in the overall quality of the company’s products.”
The deal is expected to be completed on Friday 13 November, but may require clearance from the Competition and Markets Authority.