Riley Keough has a ''giant hole'' in her heart following the death of her brother Benjamin Keough.

The 31-year-old actress has broken her silence after her younger brother Benjamin passed away last week at the age of 27 from a self-inflicted gunshot wound.

Riley shared a slideshow of images of the pair - who are both the children of Lisa Marie Presley and Danny Keough - on Instagram, and said she ''can't believe'' her sibling is gone.

She wrote alongside the pictures: ''Mornings are the hardest. I forget you're gone. I can't cry because of the fear that I will never stop. A pain that's new to me.

''You. There are no words for you. Angel is the closest I could think of. Pure light. Baby brother. Best friend. Wild man. Intellectual. Witness to my life. Twin soul. Protector. Too sensitive for this harsh world. I hope you give me strength to endure the giant hole you've left in my heart. I hope you give me the strength to eat. I hope you're cradled in love. I hope you feel my love. I hope you feel god. You are god. I can't believe you've left me. Not you sweet Ben Ben. Anyone but you. I guess this is true heartbreak. I hope we meet again. (sic)''

Riley's post comes after Benjamin's passing was officially ruled a suicide earlier this week, with the Los Angeles County Department of Medical Examiner-Coroner confirming he died from a self-inflicted ''intraoral shotgun wound''.

Following Benjamin's death, a spokesperson for Lisa Marie - who has 11-year-old twins Finley and Harper with her fourth husband Michael Lockwood - said: ''She is completely heartbroken, inconsolable and beyond devastated but trying to stay strong for her 11 year old twins and her oldest daughter Riley. She adored that boy. He was the love of her life.''