Bosses in the UK will be banned from using non-disclosure agreements to silence employees who have suffered harassment and discrimination in the workplace as part of the government’s overhaul of workers’ rights.

Ministers will on Monday night table amendments to the government’s employment rights bill to prohibit the widespread practice of using legally enforceable NDAs to conceal unacceptable behaviour at work.

If passed, the rules would mean any future confidentiality clauses in settlement agreements that sought to prevent a worker speaking about an allegation of harassment – including sexual harassment – or discrimination would be null and void.

They would also allow victims to speak freely about their experiences, while any witnesses – including employers – would be able to call out poor conduct and publicly support victims without the threat of being sued.

The changes being introduced to the bill, due to return to the Lords next week, would not affect NDAs for legitimate commercial use, such as commercially sensitive information or intellectual property in business transactions.

But they would create one of the toughest protection regimes in the world, giving millions of workers, including those in low-paid jobs, more confidence that inappropriate behaviour in the workplace would be dealt with.

After years of campaigning by activists, ministers have looked beyond high-profile cases linked to the #MeToo movement to address concerns about workers in regular employment who may not have the means or confidence to pursue their employers through the courts to challenge “gagging orders”.

Announcing the change, Angela Rayner, the deputy prime minister, said: “Victims and witnesses of harassment and discrimination should never be silenced. As the Guardian has reported on widely, this is not an issue confined to high-profile individuals or the most powerful organisations.

“The use of NDAs to cover up abuse and harassment is growing – and sadly amongst those in low-income or insecure employment across multiple industries and workplaces.

“This cannot go on. That is why we are stamping out this practice and taking action to ban any NDAs used for this purpose. My message is clear: no one should suffer in silence and we will back workers and give survivors the voice that they deserve.”

The legislation represents the biggest overhaul of workers’ rights in a generation, introducing day one rights, establishing collective bargaining bodies in vital sectors and strengthening family-friendly entitlements, as well as going further on bereavement leave and tackling “fire-and-rehire”.

Over time NDAs have become the default solution for many organisations, corporations and public bodies to settle cases including sexual misconduct, racism, and pregnancy discrimination.

Their original purpose was to protect intellectual property or other commercial or sensitive information, but reports have shown they have become commonly used to prevent people speaking out about horrific experiences in the workplace.

There have been many high-profile cases of NDAs being used to prevent victims from speaking about crimes, often forcing women and vulnerable individuals to feel stuck in unwanted situations, through fear or desperation.

They have proliferated especially in lower-income, insecure employment including sectors such as retail, hospitality and accommodation, with non-disparagement clauses also typically attached.

A report by the Chartered Institute of Personnel and Development (CIPD) last year found the use of NDAs was relatively common, with 22% of respondents to a survey of 2,000 employers saying their organisation used them when dealing with allegations of sexual harassment.

In contrast, 44% said they did not use NDAs in this way and a further 34% did not know, highlighting that awareness around their use in some organisations may be low.

The CIPD also found that most employers would not strongly object to the removal of NDAs in the workplace. Nearly half (48%) of employers would support a ban, with just 18% opposing, while 20% were ambivalent, and a further 14% did not know.

Zelda Perkins, a former PA to Harvey Weinstein who spearheads the campaign group Can’t Buy My Silence, said of the government’s plans: “This is a huge milestone, for years we’ve heard empty promises from governments whilst victims have continued to be silenced.

“To see this government accept the need for nationwide legal change shows that they have listened and understood the abuse of power taking place.

“Above all though, this victory belongs to the people who broke their NDAs, who risked everything to speak the truth when they were told they couldn’t. Without their courage, none of this would be happening.

“This is not over yet and we will continue to focus closely on this to ensure the regulations are watertight and no one can be forced into silence again. If what is promised at this stage becomes reality, then the UK will be leading the world in protecting not only workers but the integrity of the law.”

Louise Haigh, a former cabinet minister, said: “Victims of harassment and discrimination have been forced to suffer in silence for too long. Today’s announcement will mean that bad employers can no longer hide behind legal practices that cover up their wrongdoing and prevent victims from getting justice.”

Legislative changes have already been made in Ireland, Canada and the US so that NDAs cannot prohibit disclosure of sexual harassment, discrimination or bullying without it being the expressed wish of the employee.

A landmark survey of sexual harassment at work has found that one in four women have suffered work-related sexual assault.

Britain’s largest trade union, Unite, polled approximately 300,000 female members on whether they had experienced sexual harassment at work, travelling to work or from a colleague in or out of work hours.

Of the 6,615 respondents, 25% said they had been sexually assaulted and 43% had been inappropriately touched. More than 3,000 said they had been the recipient of sexually offensive jokes and/or experienced unwanted flirting, gesturing or sexual remarks.

And 28% had been shared or shown pornographic images by a manager, colleague or third party, while 8% had been a victim of sexual coercion – when a person pressures, tricks, threatens or manipulates someone into engaging in sexual activity without genuine consent – at work.

While the perpetrator in the bulk of these incidents was a member of public in the workplace, such as a patient or a passenger, 3% said they had been sexually assaulted by a manager and 6% by a colleague.