Amber Heard has challenged ex-husband Johnny Depp to double the $7 million (£5.3 million) he plans to donate to charity in lieu of a divorce payment.

Heard had pledged to donate the $7 million she received as part of her divorce settlement to a domestic violence charity and the Children's Hospital of Los Angeles.

Depp has since released a statement saying that he was going to donate this money straight to Heard's chosen charities.

Heard's legal team responded by claiming Depp's decision to pay the charities directly meant he must donate $14 million (£10.6 million) to account for tax deductions.

A spokeswoman for Heard said: "Amber Heard appreciates Johnny Depp's novel interest in supporting two of her favourite charities, the ACLU (American Civil Liberties Union) for domestic violence and the Children's Hospital of Los Angeles. This is great and unexpected news.

"However, if Johnny wishes to change the settlement agreement, we must insist that he honour the full amount by donating $14 million to charity, which, after accounting for his tax deduction, is equal to his seven million-dollar payment obligation to Amber."

A spokesman for Depp confirmed that the actor had sent "the first of multiple installments" of money to the two charities.

Depp, 53, and Heard, 30 were divorced earlier this month following a series of abuse claims that have since been withdrawn.

Heard claimed Depp had a "history of drug and alcohol abuse" and been "verbally and physically abusive" for the entirety of their four-year-relationship.

Depp denied these claims and a joint statement released by the former couple confirming their divorce agreement said there was "never any intent of physical or emotional harm".

"Our relationship was intensely passionate and at times volatile, but always bound by love," they said. "Neither party has made false accusations for financial gain."