MELBOURNE (Reuters) - BHP and Rio Tinto have used confidentiality agreements to prevent female employees from speaking about sexual harassment at work, according to a lawyer leading Australian class action lawsuits against the miners.

Brisbane-based law firm JGA Saddler filed a class action against each mining giant this week, alleging widespread and systemic sexual harassment and discrimination at Australian mine sites.

The class actions promise more headaches for the two firms, which have struggled to rebuild their public image. A 2022 Western Australia state government review of remote mining sites found women frequently dealt with sexual harassment and sexual assault. The industry has also been held to account for the destruction of Aboriginal heritage, mine fatalities and environmental disasters in recent years.

JGA Saddler has spoken to hundreds of women and seen evidence of the widespread use of non-disclosure agreements by the mining industry, lead litigator Josh Aylward told Reuters in an interview, adding some have expressed concern that the NDAs could prevent them from joining the class actions.

BHP and Rio said they do not currently use NDAs when dealing with sexual harassment allegations.

Mining companies have pressured vulnerable workers to sign agreements because they feared losing their jobs or being blacklisted from the industry, Aylward alleged.

"It's common practice," he said. "There's a lot of other industries that have matured past the use of NDAs and realised that you have to front up for earlier sins, and if people want to talk about what happened to them, then they should be able to do it."

Rio said in a statement to Reuters it would not enforce any historic confidentiality terms that prevented employees from discussing their personal experiences.

A representative for BHP referred Reuters to the company's annual report, where it said it had stopped using NDAs relating to sexual harassment claims in March 2019 and doesn't enforce past agreements.

Both companies also say they take all allegations of sexual harassment seriously and are seeking to stamp it out in the industry.

Angela Green, who worked in BHP's explosives team from 2018-2024, said in a statement she plans to join the class action. She said she was unfairly terminated for falsifying a log book, which she denies, after she had made a complaint about sexual harassment.

Green alleges she was subsequently offered compensation from BHP for the manner of her dismissal on condition she signed an agreement with a confidentiality clause.

"BHP state office said if I signed it then they would clear my record and change it to say I resigned instead of being terminated," she said.

The court filings have yet to be made public. According to a statement from JGA Saddler, the lead applicant in the BHP case alleges she was urinated on by a male co-worker, sexually harassed over a two-way radio and had another male co-worker defecate in front of her.

The lead applicant in the Rio suit alleges she was sent unsolicited sexually explicit messages as well as videos and pictures from a colleague showing him masturbating in his on-site room. After her complaint, she was overlooked for opportunities to upskill, she said in the statement.

JGA Saddler has requested the court redact the lead applicants' names in the filings amid concerns for their personal safety.

The lawsuits were filed at the Federal Court and a judge will be assigned shortly. The judge will then set out times and dates in a hearing, expected to be in February. At that time, the court will order both miners to contact all women who have worked for them since November 2003.

According to its annual report, BHP received 471 reports of sexual harassment in the 2024 financial year across its global operations. It investigated 100 cases and 103 workers were either dismissed, resigned or were removed from site if they were a contractor.

Rio said last month that cases of rape and sexual assault at its mines persisted. An investigation found eight instances of actual or attempted sexual assault.