Journalists working at the South Wales Evening Post, Carmarthen Journal and Llanelli Star have signed a petition against the company decision to remove extra pay for working Sundays.
Forty five reporters, sub-editors and photographers have signed a letter of protest condemning the move by Northcliffe-owned South West Wales Media (SWWM).
Payments for Sunday working were withdrawn after it was decided that overnight printing, resulting in more shift and weekend work, was a permanent fixture.
Overnight printing is a trend sweeping the regional press as former evening papers seek to reduce their distribution costs, by going out to newsagents with the national papers in the mornings, and also to get more time on the newsstand.
Fitzpatrick: alerting NUJ members to the trend to curb payments NEWSDESK: 020 7324 2337 The move follows a turbulent 18 months for the Northcliffe paper, which has seen editorial jobs axed and departments merged.
The extra pay was introduced just over a year ago, when the Post closed its Adelaide Street press in Swansea and switched Saturday shifts to a Sunday.
Editor Spencer Feeney said he would not comment on pay arrangements.
But in a letter to staff leaked to Press Gazette he said: "At that time, I felt it was right to offer staff an extra payment for working on Sunday, in recognition of the unusual circumstances.
"It is now clear, however, that overnight printing, and the associated working patterns we adopted, is established.
We will not be reverting to the way we previously produced our publications.
"I propose, therefore, to stop the extra payment for working on a Sunday."
An insider told Press Gazette: "The Post is probably the only paper of its kind in the UK to have a positive ABC figure for 2006, so you would expect staff to be in confident mood.
"It was our professionalism, hard work and willingness to show maximum flexibility with regard to new working practices and working hours that was in no small measure responsible for that success.
"This latest move by management is a kick in the teeth for staff, whose morale is already rock bottom."
NUJ national organiser Barry Fitzpatrick said the union was trying to alert members across the country to oppose plans to curb extra Sunday payment.
He said: "There is this huge drive for integration, new media and this whole revolution is unstoppable.
"We are not trying to stop it, we're not saying you shouldn't move with the times or move with technology, but there has to be a life/work balance.
"People have a right to ensure they have decent breaks, weekends that are weekends not some notional day or two in the middle of the week when they can't be with their families.
"If they do work weekends then money would be part of it.
"But there would also have to be guarantees that there would be a minimum number of weekends per year and the number of consecutive days that people take off would have to be protected so you don't get a Tuesday and Thursday off in place of the weekend."
The SWWM chapel is currently seeking official recognition.