SAMANTHA Markle has taken aim at Prince Harry in a sarcastic tweet sent on his birthday.

Meghan's estranged half-sister hasn't held back from commenting on Meghan's new life - despite previously admitting they hadn't spoken in more than a decade.

In her latest tweet, the 53-year-old takes a swipe at Harry for his apparent failure to send a birthday greeting to Thomas Markle, her and Meghan’s father.

Accompanied by a gif of a hamster it said: “Happy Birthday Harry! As you ‘Mack down’ on your birthday cake, think about the birthday wishes you never extended to your FATHER-IN-LAW.”

Mum-of-three Samantha Markle, also known as Samantha Grant, is a former actress and model, who lives in Florida, US.

The Duchess of Sussex has endured a stream of criticism from her since tying the knot with Harry.

The 37-year-old royal's family has been in the spotlight after dad Thomas Markle pulled out of her wedding to Harry after it was revealed he had staged photographs with the paparazzi.

Thomas, 73, who lives in Mexico, has accused the royals of freezing him out of his daughter’s life over the pictures.

A common theme of Samantha’s frequent Twitter rants are accusations that Harry and Meghan lack compassion for Thomas.

"They have unlimited resources and no interest or compassion to care. The truth sucks," she tweeted last month.

Samantha Markle has previously urged her sister to contact their father, saying the Duchess would be "responsible" if their father died.

She recently labelled Meghan a "DuchASS" and accused her of "fake waves and smiles".

"I am not candy coating anything anymore! The DUCHASS should be humane to our father who has given her everything,.. and this media crap can stop!” she tweeted.

"He was the one who was always there for her. Fake waves and smiles can stop. The duchASS can bow to the daddy."

Samantha also accused Meghan of being "cold" and last month compared her half-sister to Cruella de Vil.

Bitter Samantha shared an article that claimed the Duke and Duchess of Sussex were "taking a step away from the media spotlight".

"OK so Cruella de Vil is retreating LOL. Let me know how that works out for you,” she wrote.

In the past, Samantha has claimed to have raised Meghan for 12 years when she was growing up in California.
However, other sources speculate that the pair had little to do with one another - and were raised completely separately.