Suits actor Meghan Markle’s estranged sister is reportedly set to release a tell-all book, rumoured to out the royal ambitions of Prince Harry’s girlfriend.

Samantha Grant, Markle’s half-sister, is reportedly working on her memoirs in a book titled The Diary of Princess Pushy’s Sister, spilling secrets about Meghan’s private life, The Sun reported.

“My book deals with my bi-racial family in a candid, warm, personal and socially important way,” Grant told the Daily Star.

“Maybe when Meghan is more mature and reads the book she’ll understand. Some of it she won’t like, some of it she might.”

It’s not the first time Grant has unleashed a scathing attack on her sister, after she confirmed the 35-year-old’s romance with Prince Harry since last year.

She claimed Markle’s relationship was driven by “social climbing”.

Now, Grant – who is wheelchair bound due to multiple sclerosis – has revealed her half-sister’s childhood dream and ultimate ambition, to become a princess.

“It was something she dreamed of as a girl when we watched the royals on TV.

But Grant, 51, who branded Markle as “Princess Pushy”, says her sister has changed since entering the Hollywood spotlight.

“Hollywood has changed her. I think her ambition is to become a princess.”

“Her behaviour is certainly not befitting of a Royal Family member.

“She always preferred Prince Harry — she has a soft spot for gingers.”

Late last month, Grant labelled the American actress a “hypocrite” on Twitter.

On Sunday night (US time), Grant spoke out on exposing her sister in her upcoming book, claiming the rumours are not a threat, but a fact.

It’s not a threat it’s a fact and a good book. Just wait and see pic.twitter.com/CBljuJWtmg

— Samantha Markle (@SamanthaMGrant) April 2, 2017