Samantha Markle, 53, launched a furious tirade against her duchess sibling after Meghan and her new husband Prince Harry visited the Nelson Mandela centenary exhibition in London’s Southbank Centre.
She posted on Twitter: “How about you pay tribute to your own father?! Enough is enough.
“Act like a humanitarian, act like a woman. If our father dies, it’s on your Meg”.
It comes after it was reported Meghan and Harry are “frustrated” at Mr Markle for continuing to carry out paid interviews.
The Duke and Duchess of Sussex have reportedly not had any contact with the retired lighting director since his bombshell interview with Good Morning Britain.
Mr Markle claimed the Royal Family have distanced themselves since he opened up about Prince Harry’s political views.
Samantha continued her rant, accusing the Royal Family of being “cold”.
She tweeted: “My father is not an embarrassment for loving his daughter!
“The Royals are an embarrassment for being so cold. You should be ashamed of yourselves @KensingtonRoyal.”
Taking aim at Meghan, she added: “Glad you have so much time to gallivant around paying tribute to others while ignoring your own father!
“How cold can you be and look in the mirror? Harry? I guess I was right.”
Mother-of-three Samantha is currently penning a book called ‘Living in the shadows of the Duchess’.
Meghan Markle and Prince Harry visited the Nelson Mandela exhibition on Tuesday
Meghan Markle’s half-sister Samantha launched a furious attack on the duchess
Yesterday, it emerged the duke and duchess are fed up with Mr Markle.
A source told Entertainment Online: “They are frustrated he keeps speaking to the tabloids and taking payment for interviews.”
But Mr Markle hit back telling TMZ he would not stop talking to the media until he’s allowed in Meghan Markle’s life.
He said: “I was silent for a full year and the press beat me up every day saying I was a hermit hiding in Mexico, so I gave my story.
“Apparently that interview put the Royal Family in their silence mode so I gave another interview to break the silence. All they have to do is speak to me.”
Mr Markle has previously said he feels he has been “put in a penalty box” following his explosive tell-all interview with presenter Piers Morgan where he revealed what his son-in-law Prince Harry, 33, really thinks of US President Donald Trump.