The company has been hit with a class action lawsuit alleging decades of widespread sexual harassment across its remote worksites and accommodation village.
"You would have seen the news that a class action has been launched against Fortescue," Mr Forrest said in an email to staff on Friday.
He said the company had first been made aware of the accusations through media reports.
"They are serious. They are disturbing," he said.
"They concern behaviour that has no place at Fortescue."
According to the suit filed in the Federal Court on Thursday, a woman was pulled into a dark alley by a man who forcibly tried to kiss her and another found a random man in her room when she came home one night.
Others claimed they were subjected to vile language, including ''you sl**s report us and then we get the sack'' and ''why don't you f*** the crew, you will make yourself feel better''.
"Where conduct amounts to criminal behaviour, we will support our people and expect the law to take its course," Mr Forrest said.
"Losing your job is the beginning of the consequences, not the end."
Western Australian Liberal MP Libby Mettam, who chaired a state parliamentary inquiry into the issue, said the allegations underpinning the class action were similar to those previously identified by the probe.
In 2022, the inquiry delivered 24 recommendations largely aimed at companies improving safety and cracking down on perpetrators, including blacklisting them from the industry to prevent them from moving from one company to another.
"That inquiry uncovered a toxic culture of cover-up in the mining industry," Ms Mettam told AAP.
"Four years on, I am extremely disappointed the same allegations are being repeated.
"A workplace culture that supports the harassment and discrimination of women must be stamped out."
Ms Mettam said she would follow up with the state Labor government to demand answers.
Asked why not all of the report recommendations had been implemented, including a blacklist of offenders, WA Premier Roger Cook said there was still more to do.
"I know the industry takes these issues very seriously, particularly after those incidents or the pattern of behaviour were highlighted, and we know there's more to do," he told reporters on Thursday.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
