Johnny Depp strenuously denied being violent to his ex-wife Amber Heard and claimed a British tabloid article that accused him of being a "wife-beater" caused "serious harm" to his reputation, a London court was told on Tuesday.

The Hollywood star's denial came at the start of his defamation case in the British capital against The Sun newspaper, which made the allegations in a 2018 article.

Depp, 57, is suing The Sun's publisher News Group Newspapers (NGN) and the author of the article, executive editor Dan Wootton, for libel.

Wearing a dark suit, white shirt and facemask, he was met by a throng of waiting cameras at the court's front entrance. Heard, a 34-year-old actress, arrived by a separate back entrance.

The case is expected to lay bare the nature of the couple's relationship -- and lift the lid on the life of some of Hollywood's biggest names.

Heard and Depp met on the set of the 2011 film 'The Rum Diary', married in 2015 and divorced in 2017
Heard and Depp met on the set of the 2011 film 'The Rum Diary', married in 2015 and divorced in 2017 AFP / Giuseppe CACACE

In a written outline to the court of Depp's position, his legal team accepted the couple's relationship was at times "physical" but insisted it was at Heard's instigation.

On occasions, the "Pirates of the Caribbean" star had to defend himself from her violence, his lawyer David Sherborne said, adding: "He is not a wife-beater and never has been."

The lawyer said Heard's claims that he seriously assaulted and injured her were "complete lies" and that he had already publicly denied the assertion before The Sun published.

Both Depp and Heard were present at the first day of the London trial
Both Depp and Heard were present at the first day of the London trial AFP / DANIEL LEAL-OLIVAS

"The claimant (Depp) was not violent towards Ms Heard, it was she who was violent to him," he said.

Heard was a "complex individual who suffered extreme mood swings, would provoke endless circular arguments, and fly into violent rages", he added.

She was on a "wide range of prescribed medication and other drugs". Her behaviour, which was attention-seeking and "extremely unpredictable", included having affairs.

Depp loved her but found her behaviour "often bewildering" and "very difficult" to understand or deal with, he added.

"Ms Heard has concocted a catalogue of ever more extreme and shocking lies about him," the lawyer said, accusing her of exploiting anti-violence against women movements for her own ends.

Heard entered the court through a back entrance
Heard entered the court through a back entrance AFP / Tolga AKMEN

Depp claims the story -- "Gone Potty: How can JK Rowling be 'genuinely happy' casting wife beater Johnny Depp in the new Fantastic Beast film?" -- caused "serious harm to his personal and professional reputation".

He also suffered "significant distress and embarrassment".

The Sun's publisher News Group Newspapers (NGN) is contesting the claim, and is relying for its defence on 14 separate claims of domestic violence.

Heard alleges the assaults occurred between early 2013 and May 2016, when the couple split.

NGN argues Depp was "controlling and verbally and physically abusive towards Ms Heard, particularly when he was under the influence of alcohol and/or drugs".

Depp and Heard met on the set of the 2011 film "The Rum Diary" and married in February 2015. They settled a divorce out of court in 2017.

Heard donated a $7 million (?5.6 million, 6.2 million euros) settlement to charity.

The case was delayed because of the coronavirus outbreak and is being heard over a scheduled 15 days at the High Court in central London.

Judge Andrew Nicol said most of the hearing would be in public but parts would be in private.

As well as Depp and Heard, Depp's former partners Vanessa Paradis, the French singer, and the actress Winona Ryder are due to give evidence.

In pre-trial witness statements Paradis -- Depp's former long-time partner with whom he has two children -- has described the actor as "kind" and "non-violent".

Heard has said she suffered a "three-day ordeal of physical assaults" in Australia in 2015.