The chief of Ford Motor Company has apologized to employees at two factories in the US city of Chicago and promised changes, after a scathing expose detailed decades of sexual harassment and abuse.

The New York Times published an extensive account earlier this week of pervasive harassment and mistreatment of women at the factories dating back to the 1990s.

More than 70 current and former employees claimed a hostile culture where women were retaliated against for reporting misconduct or discouraged from doing so.

In an open letter to employees sent Thursday, the auto giant's chief executive Jim Hackett said he had "read and reread the article," which he found "gut wrenching."

"I am sorry for any instance where a colleague was subjected to harassment or discriminatory conduct," he said, promising "zero tolerance" for sexual harassment.

"On behalf of myself and the employees of Ford Motor Company, who condemn such behavior and regret any harassment as much as I do, I apologize. More importantly, I promise that we will learn from this and we will do better."

The revelations expanded the cultural reckoning over abuse and harassment, resulting from the #MeToo campaign, into the blue-collar world and the heart of the auto industry.

The harassment alleged at the Ford plants, including the oldest continuously operating factory of the American auto giant, was at times severe and sometimes involved serial offenders, according to the Times investigation.

In one account, a female employee said she was pressured to have sex with a male supervisor and relented to improve her working conditions.

Hackett said he would visit the Chicago Assembly and Chicago Stamping plants to speak with employees directly.

"This has been a learning experience about how difficult it can be to root out bad behavior," he said.

There have been efforts over the years to change the culture at the plants, whose workforce is more than two-thirds men.

Ford has settled lawsuits, reached agreements with the federal agency that monitors workplace discrimination, and set up a $10 million fund to help women.

Ford and the United Auto Workers union have also invested in training, and the company has established independent monitors.

But, the company failed to combat retaliation against whistleblowers, delayed punishing offenders, and did not maintain sexual harassment training, according to The Times.

Hackett pledged to do more.

"Our promise is there will be no retaliation against anyone who speaks up, and no one is above the rules, no matter where they are in the hierarchy," he said.