LONDON -- Johnny Depp denied assaulting ex-wife Amber Heard on a private Caribbean island and during a furious rampage in Australia in a third day of evidence Thursday in his libel suit against a tabloid newspaper that called him a "wife-beater."

Depp is suing News Group Newspapers, publisher of The Sun, and the paper's executive editor, Dan Wootton, over an April 2018 article that said he'd physically abused Heard. He strongly denies being violent to Heard.

Under cross-examination by The Sun's lawyer, Sasha Wass, Depp depicted a volatile relationship with Heard, during a period when he was trying to kick drugs and alcohol and sometimes lapsing. He said he came to feel he was in a "constant tailspin" but denied being violent.

Depp rejected Heard's claim that he subjected her to a "three-day ordeal of assaults" in March 2015 in Australia, where Depp was filming the fifth "Pirates of the Caribbean" movie.

"I vehemently deny it and will go as far as to say it's pedestrian fiction," he said.

He said his relationship with Heard was a "constant barrage of insults and demeaning footnotes and accusations of things that never happened."

Depp and Wass sparred over disputed details of the Australia episode, which ended up with the couple's rented house being trashed and Depp's fingertip being severed to the bone.

Depp accuses Heard of cutting off his fingertip by throwing a vodka bottle at him. She denies being in the room when the digit was severed.

According to Heard, Depp snorted cocaine, swigged Jack Daniels from the bottle, smashed bottles, screamed at Heard, threw her against a ping pong table and broke a window.

"These are fabrications," he said.

He denied taking drugs but agreed that the couple had argued and at one point he "decided to break my sobriety because I didn't care anymore. I needed to numb myself."

Wass also alleged that Depp had lashed out at Heard during an attempt to break an addiction to the opioid Roxicodone on his private island in the Bahamas in 2014. He denied physical violence, but said Heard's claim that he was "flipping" and "screaming" might be accurate.

"I remember that I was in a great deal of pain and uncontrollable spasms and such. … So flipping could be a word that was correct," he said.

"I was not in good shape. It was the lowest point I believe I've ever been in in my life."

Depp accused Heard of telling "porkie pies" -- slang for lies -- about his behaviour. He acknowledged striking out at objects, saying it was better than "taking it out on the person that I love."

He denied he could have been physically abusive and not remember it.

"There were blackouts, sure, but in any blackout there are snippets of memory," Depp said.

On Wednesday Depp acknowledged that he may have done things he can't remember while he was under the influence of alcohol and drugs.

"I may have done things that I have no memory of," Depp said. But he insisted "I am certainly not a violent person, especially with women."

The Sun's defence relies on a total of 14 allegations by Heard of Depp's violence between 2013 and 2016.

The case is shining a light on the tempestuous relationship between Depp and Heard, who met on the set of the 2011 comedy "The Rum Diary" and married in Los Angeles in February 2015. Heard, a model and actress, filed for divorce the following year and obtained a restraining order against Depp on the grounds of domestic abuse. The divorce was finalized in 2017.

While neither Heard, 34, nor 57-year-old Depp is on trial, the case is a showdown between the former spouses, who accuse each other of being controlling, violent and deceitful during their tempestuous marriage.

Wass read the court an email to Depp that Heard had composed in 2013 but never sent, saying he was "like Dr Jekyll and Mr Hyde. Half of you I love madly, and the other half scares me."

Depp accused Heard of making up "hoax" abuse claims. He has acknowledged heavy drinking and drug use, but said Heard's claim that drugs and alcohol made him a monster was "delusional."

He also denied claims he hit Heard when she laughed at one of his tattoos, dangled her Yorkshire terrier, Pistol, out a car window and threatened to put the dog in a microwave.

Depp acknowledged having a "rather skewed" sense of humour and said the microwave comment was a running joke because the dog was so tiny.

Heard is attending the three-week trial and is expected to give evidence later.

Depp is also suing Heard for US$50 million in the U.S. for allegedly defaming him in a Washington Post article about domestic abuse. That case is due to be heard next year.