Some 50 people at The Herald and Sunday Herald have applied for voluntary redundancy as part of Newsquest's drive to cut between £2 million and £3 million, according to the NUJ.
NUJ Scottish organiser Paul Holleran said if staff numbers are reduced by such an amount the titles would be "unsustainable".
- November 1, 2017
- October 13, 2017
- September 13, 2017
But Newsquest Scotland has written to the Department for Trade and Industry to declare it is seeking between 22 and 99 redundancies, a figure that will likely depend upon the salary range of those leaving.
The 50 volunteers to date equate to around a quarter of the workforce on the two titles. Redundancies are also being sought on the Evening Times in Glasgow.
The NUJ is launching a petition to hand to the Scottish Parliament at Holyrood and at Westminster, calling on them to support the union's campaign to protect the status and integrity of the papers.
The petition is due to be handed in during the first week of the new Parliament at the end of May.
There are an estimated 300 editorial staff working across the Newsquest Scotland titles and around 16 in the magazines.
Chief executive Tim Blott was due to meet journalists this week for a question and answer session where Holleran expected he would be quizzed over assurances that were given by Newsquest at the time of the takeover.
Newsquest bought the titles from Scottish Media Group between December 2002 and March 2003 for an estimated £216 million.
Holleran said: "At the time of the takeover the company said to the Competition Commission that it would recognise the diversity and that it wouldn't impinge on the quality of the papers.
"As far as we are concerned it is breaching those assurances. It will be unsustainable. People are already working excessive hours.
"Industrial action will be triggered by any compulsory redundancies.
"If enough people volunteer for redundancy then we have to get answers from the company about how they are going to sustain the production of these quality titles."
Blott was unavailable for comment.