Hollywood actor Johnny Depp on Wednesday denied claims that he slapped his ex-wife Amber Heard, as he faced a second day of questioning in his high-profile libel trial in London.

The "Pirates of the Caribbean" star is suing British tabloid The Sun for a 2018 article which claimed he was a "wife-beater."

Both Depp, 57, and Heard, 34, were in court as lawyers for The Sun's publisher, News Group Newspapers (NGN), questioned him about allegations of violence during the couple's time together.

The couple first met on the set of the 2011 film "The Rum Diary," married in 2015 but Heard filed for divorce 15 months later.

NGN is disputing the claim for libel, and said there is "overwhelming evidence" that he attacked Heard while under the influence of drink and drugs between 2013 and 2016.

'Wino Forever'

Lawyer Sasha Wass, representing NGN, put it to Depp that he had slapped Heard three times after she made fun of a "Wino Forever" tattoo on his arm in March 2013, the first alleged incident of violence, when he was drinking heavily.

"I'm sorry but that is not true, you are mistaken... I didn't hit Ms Heard," the actor replied.

The tattoo originally read "Winona Forever" and referred to the actress Winona Ryder, with whom he had had a previous relationship. He changed it after they broke up.

A 'blind rage'

NGN is relying on 14 separate claims of domestic violence in its defense, all of which Depp denies.

On Wednesday, Depp was accused of abusing Heard on a flight from Boston to Los Angeles following a row over James Franco, who appeared with her in the film "The Adderall Diaries."

Depp told the court that he was surprised she agreed to make the film with Franco, having previously described him as "creepy" for making aggressive sexual advances towards her.

On the flight, Depp screamed obscenities at Heard and kicked her in the back in a "blind rage," as she tried to walk away from him and slapped her across the face, said Wass.

A hoax built up over years

Earlier Depp said Heard's allegations were a hoax built up over years during their relationship as an "insurance policy."

In an unsent email composed by Heard in June 2013, three years before she publicly accused him of abuse, she said Depp had hurt her physically and that she did not know if she was dealing with him or "the monster," his alter ego brought on by anger, jealousy and fueled by alcohol and drugs.

Asked if the email meant Heard had been plotting the allegations for three years, Depp said: "By the evidence that I have seen. It appears to me that Miss Heard was building a dossier that appears to be an insurance policy for later."

'I never abused Heard': Depp

The case, expected to last for three weeks, opened at the High Court on Monday with Depp insisting in a witness statement that had "never abused Ms Heard, or, indeed any other woman" in his life.

He said Heard, was calculating, sociopathic, narcissistic and emotionally dishonest, with a diagnosed borderline personality disorder, and was intent on destroying his life.

Much of the questioning has involved his drinking and drug-taking but he insisted he did not have a "nasty side" and lost control while under the influence, as Heard has asserted.

His legal team called Heard's allegations "complete lies." They said she was a "complex individual," prone to wild mood swings under a variety of prescription medication and other drugs.

Rather than Depp being the perpetrator, she had subjected him to verbal and physical attacks, and he had had to defend himself on occasions, they argued.

"He is not a wife-beater and never has been," his lawyer David Sherborne said.

Depp maintains The Sun article, which was published despite a previous public denial of violence, had caused "significant reputational damage" to his career.

(With input from AFP and Reuters)