The Duchess of Sussex's half-sister says Meghan 'faked' Archie's christening

Samantha Markle says she's surprised "the church didn't catch fire" when Meghan walked in. Photo / Supplied

Samantha Markle, sister of Meghan, the Duchess of Sussex, has slammed her sibling for "faking" baby Archie's christening.

The Sun reports that Samantha Markle has called her sister a "disgrace" to the family, just as the Duchess prepares to celebrate her first birthday as a mum this weekend.

The 54-year-old sister of the Duchess called her "callous" and "shameful" and said she hopes Archie doesn't grow up to treat her like she "treated dad".

This is a U-turn from the apology that Samantha Markle made public a few months ago, when she claimed to regret the negative things she'd told the media about her sister.

"I'm surprised the church did not catch fire when she walked into it," she said of her nephew's christening last month.

"For my sister to go into a church knowing what she has done to our father, ignoring him through every holiday, the wedding, two heart attacks the birth and the christening, is disrespectful.

The Duchess celebrates her first birthday as a mum this weekend. Photo / Getty Images

"Everything about the christening look faked and photoshopped but more at issue is the fact that she has traded an entire family to be royal and shame on her."

The 54-year-old says she "feels sorry for the baby" for "having a mother like that".

"He will grow up to know how controlling she is and that she knowingly and willingly hurt higher family but more than that Archie's grandfather [Thomas Markle] who is incredible and should have been in his life," she added.

Samantha Markle's comments come just days after the announcement of the Duchess' guest edition of Vogue UK.

Prince Harry's sister-in-law is working on her book, which was initially titled "The Diary of Princess Pushy's Sister". The title has since been revised to "A Tale of Two Sisters".

She says the book will include details of her "home life".