The union said 16 production staff at the Ceredigion-based company are set to walk out for half a day this afternoon followed by two more half-days and nine 24-hour strikes, on Wednesdays for the next 12 weeks.

Unite accused the company of trying to force through changes to its sick pay scheme and of a "culture of bullying and harassment of union members".

Regional officer David Lewis said its members had voted "overwhelmingly" in favour of industrial action.

"The unanimous support for action is testament to the terrible treatment that our members have been on the receiving end of.

"We’ve had countless reports of local officials and union members being bullied. The company needs to take heed of what its employees are telling them by the ballot – the culture needs to change and the workforce needs to be treated with decency and respect," Lewis added.

Unite national officer Steve Sibbald accused the management of Gomer Press of "having its head firmly stuck in the sand".

He said: "Gomer Press claims that bullying and harassment does not exist but our members insisted it went down on the ballot sheet, which shows how strongly they feel about it and suggests the company is in denial.

"Our members have complained about being ostracised and ignored by management which has taken a hostile attitude towards them."

Sibbald added that Gomer Press had refused to negotiate with Unite on its staff’s annual pay increment and had pushed through a 2% rise.

"Every year for as long as people can remember, we have always had negotiations around annual pay increases. We have taken on board what the company says, and vice versa. This year the company imposed a 2% pay increase and ignored our claim for an increase in line with RPI, which was 3.8%"

"There was an 11th hour meeting on Monday between Gomer Press, Unite representatives and the BPIF, but the company refuses to budge."

Gomer Press said it would issue a statement later today.