The company has not revealed the total number of redundancies it requires, but the figure is believed to be in the range of 550 and 770 jobs -- between 5% and 7% of the workforce of approximately 11,000.
Staff in Cardiff, Newcastle and Middlesborough were informed this week of the cuts and offered the chance to take voluntary redundancy, while a similar announcement is expected in Liverpool today.
The affected newspapers include the Newcastle Evening Chronicle and the South Wales Echo.
A Trinity Mirror spokesman said: "This is a locally-driven process and each operating company has its own timetable for consultation. However, the overall process will not be concluded before our preliminary results announcement on March 2, 2006."
The review was announced by chief executive Sly Bailey following poor advertising revenues for the national newspapers in the group's first-half results, reported in July.
Trinity's five national papers, which include the Daily Mirror and the Daily Record, saw ad revenues slump by 5.4% from £99m to £93.7m, in a market that the company called "unpredictable". In contrast, the regional division saw ad revenues grow 1.5% to £214.1m.
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