Lisa Marie Presley's estranged husband MICHAEL LOCKWOOD has told courts he's concerned the singer could ''relapse into drug and alcohol dependency'' following her son's tragic death.

Lisa Marie's 27-year-old son Benjamin Keough took his own life earlier this month, and her former spouse Michael has now said he believes the tragedy could push the 52-year-old singer - whom he split from in 2016 after a decade of marriage - over the edge.

Michael filed documents with courts last week ahead of the former couple's custody trial - which is set to begin on August 3 - in which he asked for Lisa Marie to be stripped of primary custody of their 11-year-old twin daughters, Finley and Harper, for the ''safety of the children''.

According to papers obtained by The Blast, Michael said: ''Lisa Marie Presley's son shot and killed himself in her home (Although she was not there at the time.) With all due sympathy and respect, this creates a new and unaddressed twofold problem: the safety of the children and the greater likelihood of [Presley] to relapse into drug and alcohol dependency.''

Lisa Marie has been open about her struggles with an addiction to painkillers and opioids, and last year detailed her battle in the foreword for Harry Nelson's book 'The United States of Opioids: A Prescription for Liberating a Nation in Pain'.

She wrote at the time: ''You may read this and wonder how, after losing people close to me, I also fell prey to opioids.

''I was recovering after the [2008] birth of my daughters, [Harper] Vivienne and Finley, when a doctor prescribed me opioids for pain. It only took a short-term prescription of opioids in the hospital for me to feel the need to keep taking them.''

And in the book, Lisa Marie credited her four children - including 31-year-old Riley Keough - with giving her ''the purpose to heal'' from her addiction.

She penned: ''As I write this, I think of my four children, who gave me the purpose to heal, [after considering] the countless parents who have lost children to opioids and other drugs.

''[I'm] grateful to be alive today ... and to have four beautiful children who have given me a sense of purpose that has carried me through dark times.''