A former employee of the late billionaire Mohamed al-Fayed has said that he “raped and brutally abused” her when she worked at the luxury British department store Harrods, and that his brother was aware of her trafficking.

The account, detailed in an American court filing on Tuesday, said that Ali Fayed, Mr. al-Fayed’s younger brother, may have evidence showing that Harrods was complicit in the widespread sexual abuse of company employees by its owner Mr. al-Fayed, and in its coverup.

Ali Fayed, who is 80 and has a residence in Greenwich, Conn., is a former director of Harrods and the current chairman of a 139-year-old British shirt maker that supplies the royal family.

The woman, identified in the court documents as Jane Doe because she said she fears retaliation, is a permanent resident of the United States, and made the accusations in a petition to the Federal District Court in Connecticut. The filing does not directly bring legal claims against Ali Fayed; instead, it lays the groundwork for evidence to be collected for legal disputes in other countries.

The details in the filing are the latest in a series of allegations of abuse made against Mr. al-Fayed, who is accused of using Harrods as a hunting ground for young women after he bought the department store with his two brothers, Ali and Salah, in 1985. His alleged crimes have been compared to those of Harvey Weinstein and Jeffrey Epstein in their scale and systematic nature.

The new accusations throw a spotlight on the role of Ali Fayed amid increasing public outrage over the alleged abuse, the people who are said to have enabled it, and the fact that Mr. al-Fayed never faced a public reckoning before his death last year at the age of 94.