The Duchess of Sussex has said she could not be expected to "just be silent" if the Royal Family is playing an "active role" in "perpetuating falsehoods" about her.
Meghan made the remarks which have been released in a second teaser clip for the heavily anticipated TV interview with Oprah Winfrey which airs on Sunday 7 March in the US.
Harry and Meghan are expected to lift the lid on their short period as working royals together before stepping back from their duties to pursue a new life in America.
The duchess says she is not afraid of the consequences of speaking out during the 30-second clip, before adding that "a lot... has been lost already".
Winfrey asks Meghan: "How do you feel about the Palace hearing you speak your truth today?"
She replies: "I don't know how they could expect that, after all of this time, we would still just be silent if there is an active role that The Firm is playing in perpetuating falsehoods about us.
"And, if that comes with risk of losing things, I mean, I ... there is a lot that has been lost already."
CBS has shared the clip as Buckingham Palace said it had launched an investigation into claims the duchess bullied former royal staff.
Past and present employees are to be invited to speak in confidence about their experiences of working for Meghan, after it was alleged she drove out two personal assistants and staff were "humiliated" on several occasions.
The Times newspaper has reported the duchess "destroyed" one member of staff and another was left in tears before she departed.
There has long been speculation about the atmosphere in the Sussex household after a number of staff left.
The Duke and Duchess of Sussex have said they are the victims of a calculated smear campaign following the allegations.
Lawyers for the couple have said the claims are based on "misleading and harmful misinformation".