It's no secret that Sex And The City co-stars Sarah Jessica Parker and Kim Cattrall have a strained relationship.

But Kim has just let rip at SJP over the message she sent regarding Kim's late brother Chris, who died this week unexpectedly.

Taking to Instagram to blast her "cruel" fellow SATC actress, Kim told Sarah she's "not family".

"My Mom asked me today 'When will that @sarahjessicaparker, that hypocrite, leave you alone?' Your continuous reaching out is a painful reminder of how cruel you really were then and now," Kim raged.

(Image: kimcattrall/Instagram)

"Let me make this VERY clear. (If I haven’t already) You are not my family. You are not my friend. So I’m writing to tell you one last time to stop exploiting our tragedy in order to restore your ‘nice girl’ persona."

She then linked to a story about the 'Mean Girl' culture that left the friendship between the Sex And The City co-stars in tatters.

"I don't need your love or support at this tragic time @sarahjessicaparker," Kim added.

Her jawdropping rant came days after SJP reached out to Kim with a condolence message after Kim's brother was found dead last Sunday.

Under Kim's post revealing the tragic news, Sarah shared: "Dearest Kim, my love and condolences to you and yours and Godspeed to your beloved brother. Xx."

(Image: @KimCattrall/Twitter)

Cynthia Nixon, who played Miranda Hobbes, had also called the star to offer her condolences.

Kim later thanked Cynthia for getting in touch, saying: "Cynthia, hearing your voice meant so much to me. Thank you for reaching out. Love Kim #SexandtheCity."

She also wrote on the post, sharing: "Hey Kim such awful news. So sorry to hear. Sending you love. XO."

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On Tuesday Kim returned to social media to thank everyone for the outpouring of support after she announced the sad news - including her SATC co-stars.

She wrote: "I would like to thank my fans, friends and my Sex and The City colleagues for the outpouring of support for myself and family over the past 72 hours."

Kim, best known for her role as Samantha Jones, tweeted on Sunday: "It is with great sadness that myself and my family announce the unexpected passing of our son and brother, Chris Cattrall.

"At this time we ask for privacy. We want to thank you all on social media for your outpouring of love and support in this trying time."

Hours earlier the actress had asked her fans to help spread the word to find her 55-year-old brother, who had been missing for several days.

(Image: kimcattrall/Instagram)

(Image: Getty Images) (Image: Channel 4)

The actress posted a picture of her "one of a kind" brother Christopher on social media and urged people to contact police in Blackfalds in Alberta, Canada if they see him.

Local police confirmed to CNN that her brother's body was discovered on his rural property in Blackfalds, Alberta, Canada. A cause of death was not given, but police said it was not considered suspicious.