Meghan Markle's half-sister is doubting the future Royal's motives behind her humanitarian work and has called on her to support their struggling father.

The former Suits star, who is set to marry Prince Harry in the spring, has travelled around the world to support various causes. She has made trips to India to promote better education for girls and to Rwanda in support of clean water.

"I've seen in my lifetime a lot of situations where celebrities visit a place which is poverty stricken and they're wearing impeccable clothing, they themselves are wealthy," Meghan's half-sister Samantha Markle told Australian outlet Nine News.

"And it really feels like just a photo opportunity, so that is a little exploitative in my mind."

Samantha, who is writing a tell-all book about her famous younger sister, reportedly told Meghan to "step up to the plate" and help their bankrupt father pull himself up financially. Samantha is critical of Meghan failing to make their father's welfare "a priority".

According to Sky News, award-winning lighting director Thomas Markle has lived a reclusive life in Mexico since declaring bankruptcy in 2016. Thomas, who is said to only have a few hundred dollars to his name, is expected to walk his daughter down the aisle when she marries Harry at Windsor Castle in May.

Meghan Markle
Meghan's half-sister Samantha Markle said the family were always very close Samantha Markle/Instagram

Samantha feels Meghan "owes" their father for helping to launch her successful acting career. The 53-year-old said: "I think he did help her a lot and he is very creative too and encouraging, so she made the most of her environment."

Speaking from her Florida home, the writer added: "I don't think he feels that she owes him, but that is how I see it."

Referencing Meghan's gorgeous black dress in the couple's official engagement photos, Samantha added: "If you can afford $75,000 (£53,535) for a dress, you can afford $75,000 to help your dad. That's how I feel, that's who I am.

"Honestly - what she could spend in a weekend would greatly help dad, so that should be a priority. I think you need to step up to the plate and make sure he is well taken care of."

Samantha, who has not spoken to her 36-year-old sister in three years, said she asked Meghan to provide financial help for their father but has not received any.

Last month, Samantha spoke to the Mirror and said she still hoped to be invited to the Royal wedding.

"I'm in a wheelchair. I don't know that it's that easy to travel. But if I were invited I would find a way, out of love and respect," she said in an interview. Samantha suffers from multiple sclerosis and is a wheelchair user.

"I would never be disrespectful or make her feel that I wasn't' sharing her joy. I would be honoured to go — but that will come down to Meghan and her heart. It will be what it will be."