Tom Petty's cause of death is still yet to be confirmed.

The music legend passed away earlier this month at the age of 66 after being rushed to hospital following a cardiac arrest, but although his death certificate has now been released, the official cause of death is still unknown.

In the document, which was filed with Los Angeles county and obtained by, the immediate cause of death was listed as ''deferred'', but gave no further details into the star's tragic death.

The news comes after it was previously reported that although an autopsy had been completed on the 'Free Fallin' hitmaker, ''it was clear further tests needed to be done.''

Since Tom's passing, touching tributes have been pouring in, with pop megastar Taylor Swift claiming she ''idolised'' the musician.

She said: ''To me, Tom Petty represented a kind of songwriting I idolised: complex simplicity. It said so much in the lyrics, the concepts, the stories, the message, the nuances ... but always brought you back to a hook that got stuck in everyone's head. He motivated thousands of guitarists to learn to play just because they wanted to be able to play 'Free Fallin'. Count me as one of them.''

Bob Dylan - who co-founded supergroup Traveling Wilburys with Tom alongside George Harrison, Jeff Lynne, and Roy Orbison - also paid tribute to his late pal.

Bob, 76, said in a statement: ''It's shocking, crushing news. I thought the world of Tom. He was a great performer, full of the light, a friend, and I'll never forget him.''

Meanwhile, Tony Dimitriades, longtime manager of Tom Petty and The Heartbreakers, confirmed the musician had passed away.

He said in a statement: ''On behalf of the Tom Petty family, we are devastated to announce the untimely death of our father, husband, brother, leader and friend Tom Petty. He suffered cardiac arrest at his home in Malibu in the early hours of this morning and was taken to UCLA Medical Center but could not be revived. He died peacefully at 8:40 p.m. PT surrounded by family, his bandmates and friends.''