Striking Royal Mail workers have allegedly been suspended or even dismissed for using the word "scab" on social media, a union claims.
According to the Communication Workers Union, more than 150 of its members at the postal giant are currently suspended directly as a result of a wave of industrial action.
Royal Mail says the figure is just over 70, but acknowledges there have been 375 disciplinary cases since strikes began last year.
The CWU says a disproportionate number of those suspended are its reps within the company.
It claims a large number of the suspensions involve the alleged use of the word “scab” - a name given to workers who break strikes and cross picket lines - either in depots or in personal posts on social media.
A CWU spokesperson said: “At no point have these cases involved intimidation. In fact, it is the company that has questions to answer on this front.”
The union added: “We are seeing a level of attacks, suspensions and dismissals of CWU representatives that we have never witnessed before.
“This is a clear attempt to remove the union from the workplace and produce a lower paid and compliant workforce.”
The union is locked in a row with Royal Mail management, led by under fire boss Simon Thompson, over pay, conditions and job security for staff.
More than 115,000 postal workers have already carried out a series of strikes.
Labour MP Ian Lavery said the number of suspensions “looks like discrimination.”
Royal Mail allegations against those who are suspended cover various behaviours, including offensive and bullying language.
It added that “inappropriate use of social media, including the use of the word ‘scab’, is a contributory factor in a disciplinary decision.”
A spokesperson added: “In a strike setting, the term ‘scab’ has been a widely recognised derogatory term used to cause offence and intimidation for decades.
“This language has no place in any civilised workplace.
“We have zero tolerance for any form of bullying or harassment, and we will investigate every incident and allegation and take swift action to discipline the individuals involved appropriately.
“Since the start of the industrial action, Royal Mail has regularly reminded colleagues about appropriate behaviours and use of language online and in person.
“This included a specific communication highlighting that ‘scab’ was inappropriate when directed at a fellow colleague.”
Royal Mail has been accused of keeping tabs on posties - including flagging when they are stood still.
A Commons hearing this week was told about digital devices that workers carry that can monitor their movements.
Royal Mail chairman Keith Williams says he met CWU general secretary Dave Ward last week.
Further meetings will be “overseen by the board,” Mr Williams told a meeting of the Commons Business, Energy and Industrial Strategy Committee.
