Protests will be held today as controversial new fees come into force for workers taking an employment tribunal case.
Unions and employment lawyers predicted “chaos” as employees will have to pay up to £1,200 to have cases of unfair dismissal and discrimination heard.
Unite said it will pay legal fees for its members while the GMB will stage a protest outside an employment tribunal in central London.
Unite general secretary Len McCluskey said: “What we are seeing today is injustice writ large as this worker-bashing Government takes a sledgehammer to workers’ rights – this is a throwback to Victorian times.
“Seeking redress for unfair dismissal and discrimination and other injustices in the workplace is a fundamental human right – but now Ministers are putting up insurmountable financial hurdles for working people in pursuit of justice.
“We estimate that this will affect 150,000 workers a year. This is not an aid to economic recovery but a means to keep working people frightened and insecure.
“Unite will not stand idly by and let its members suffer such treatment – and the union will financially support members at employment tribunals.
“We will be campaigning strongly for this pernicious legislation to be repealed with the advent of a Labour government.”
Andy Prendergast, of the GMB, said: “The imposition of such fees represents the latest in a number of attacks on employment rights by the Government.
“Bad employers are being given the green light to continue exploiting their staff.
“The charging of £1,200 effectively means that many workers will lose any chance they had to seek redress if they are poorly treated.”
Elizabeth George, a barrister in the employment team at law firm Leigh Day, said: “This sends a very dangerous message to employers who will be less inclined to abide by their legal obligations as the risk of being challenged will be much reduced.
“These fees will disproportionately hit those suffering discrimination because of their age, race, disability and gender, with women returning from maternity leave particularly hard hit as they’ll be judged on their salary when they left rather than their statutory maternity pay.