Journalists at the Daily Record and Sunday Mail are to go on strike for a further two days in response to 24 staff members losing their jobs.
Before being told of the job losses on Wednesday, they had already planned to hold a second strike on Friday.
Following an emergency meeting they have now agreed to strike for a further two days next week.
The company said it was taking action to safeguard the future of the papers in a rapidly changing media landscape.
It added that it was consulting with those at risk of redundancy until 30 April.
The 24 members of staff were given the redundancy news by managers on Wednesday.
One member of staff said journalists across all titles and departments, including news, sport and production, appeared to be affected, including newer members of staff as well as experienced journalists who had been working on the newspapers for a number of years.
The journalist said some of those losing their jobs were told not to go back into work.
The National Union of Journalists called an emergency meeting where about 200 members of staff agreed to two further days of industrial action.
They also passed a motion of no confidence in managing director Mark Hollinshead and human resources manager Lesley Somerville, and expressed disgust at the way staff had been treated.
They also called for an immediate reinstatement of those affected.
A spokesman for the Daily Record and Sunday Mail Ltd said the company was looking at the possibility of redeployment across the group.
"The editorial restructure is a response to the current economic environment and the rapidly changing media landscape and it is absolutely vital that we take action now to safeguard the future of our newspapers," he said.
"While we have worked hard to achieve the reduction of staff numbers by voluntary means we are now consulting with 24 staff whose positions are now at risk of compulsory redundancy.
"We fully appreciate that this is difficult for all involved and obviously we would prefer to avoid industrial action as it benefits no-one."
Members of the NUJ are due to hold a second strike on Friday after owner Trinity Mirror said it wanted to shed 70 jobs after merging production of the two titles.
A 24-hour strike was held last Saturday.
James Doherty, president of the NUJ, said: "Trinity Mirror's treatment of these titles is nothing short of shameful.
"The Daily Record and Sunday Mail were brought to their knees by the greed of Robert Maxwell and today, journalists have fallen foul of the greed of Trinity Mirror shareholders.
"The NUJ will continue to fight for those who have been sacked and for those who continue to be threatened with redundancy.
"It's a sorry day for Scottish journalism - and our role in a healthy democracy - when our members are being escorted from the building with boxes and bags of their personal belongings."
The NUJ believes this is the first time in 14 years in Scottish papers that journalists have lost their jobs in this manner.
The company announced proposals in February to cut 70 out of 276 editorial staff in a bid to make the titles better equipped for what it described as a "dramatically different media economy."
It has since announced that the number has been reduced to 57.
NUJ Scottish organiser Paul Holleran said more than 40 staff members had applied for voluntary redundancy.
But he accused Trinity Mirror of refusing to accept a compromise solution which would avoid 30 compulsory redundancies.
Of the 200 NUJ ballot papers returned, 85% backed strike action. Union members also voted to implement a work to rule.
According to NUJ figures, before Wednesday's announcement Trinity Mirror had axed 234 editorial jobs in regional and Scottish national titles since last June.
The Daily Record's circulation has dropped to about 336,000, allowing it to be overtaken by the Scottish Sun as Scotland's most-bought daily newspaper, according to official ABC figures.
The circulation of the Sunday Mail has also fallen in recent times to a current level of 416,169, but it has retained its position as the country's most popular Sunday newspaper.
The most recent records show that Trinity Mirror made operating profits of more than £145m in 2008 - of which £68m came from local media. The company's profit margin is almost 17%.
In the last 10 years it has returned more than £520m to shareholders.