Johnny Depp cut off his fingertip in a booze-fuelled rage over suspicions Amber Heard was cheating on him with another actor, according to an explosive report.

In the latest disturbing twist in the couple's acrimonious divorce, TMZ reports Depp dipped his bloody stump in blue paint and used it to scrawl the names of Heard and her suspected lover, Billy Bob Thornton, on a mirror.

TMZ claims the shocking incident unfolded in an Australian villa in March last year, a month after they tied the knot.

Read more: What went on during Amber Heard's seven-hour long deposition


Depp was filming the fifth instalment of the Pirates of the Caribbean franchise on the Gold Coast at the time.

The gossip website shared grisly photos of the mutilated finger and graffitied mirror, which were exhibits in Heard's domestic violence case against the Edward Scissorhands star.

Heard, 30, claims Depp was drunk and high on ecstasy when he smashed bottles and windows, and slammed a plastic phone against the wall.

She said the father-of-two severed his finger during the rampage.

Heard had recently filmed a movie with Thornton, and she claims Depp believed she'd had an affair with her co-star. She denies cheating on Depp.

The Rum Diaries actress claims Depp scrawled the words "Starring Billy Bob and Easy Amber" on the mirror with blue paint during his drug-induced rampage.

Heard also claims in the court papers that Depp didn't seek medical treatment for 24 hours, saying doctors had to use skin from his hand to create a new fingertip.

The Telegraph in the UK reports the accident delayed filming of Pirates of the Caribbean for two weeks, as Depp flew from the Gold Coast to the US for surgery.

At the time, the production team said the actor's injury was an on-set accident.

The shocking news comes after video surfaced showing Depp getting angry with Heard and throwing a wine glass.

In the clip, the 53-year-old Pirates of the Caribbean star can be seen swearing and banging cupboard doors while Heard - who is secretly filming the exchange on a mobile phone - asks him what's wrong.

At one point Heard apologises and mentions they had previously been "having a nice morning".

She then asks Depp if he drank the wine from the half-empty bottle that is sitting on the bench, which sends him into a rage. He then realises he is being filmed and grabs the phone.

Read more: A leaked tape shows Johnny Depp smashing things and yelling at Amber Heard

Depp and Heard will face each other in court later this month. The defendant and his legal team are reportedly "locked and loaded" with nearly 24 witnesses and a secret photo to support his defence against Heard's allegations.

The pair wed in 2014 and filed for divorce this year.