Johnny Depp has failed to stop his ex-wife Amber Heard from watching him give evidence in a libel case over allegations of domestic abuse.

The actor is suing the publisher of the Sun, News Group Newspapers (NGN), and its executive editor, Dan Wootton, over a 2018 article which described Depp as a “wife beater”.

The article was referencing claims made by Heard, 37, that Depp was physically abusive to her during their marriage. He denies these allegations.

The case is due to be heard in court on Tuesday, after a last-ditch attempt by NGN’s legal team to get the case thrown out of court failed earlier this week.

Depp, 57, had sought to break with precedent for civil cases and ban his former partner, arguing that her evidence would be more reliable if she was not present in court when Depp was cross-examined.

In criminal cases, witnesses cannot be present in court while others are giving evidence, but in civil cases this is possible.

In a court order published on Saturday, however, Justice Nicol rejected the attempt, ruling that it would be “unfair” and “inhibit … the conduct of their defence”.

While the judge acknowledged that Heard was “not a party”, he said defendants NGN and Wootton “rely heavily on the information which Ms Heard can provide”.

“[Heard] will not be in a position to give instructions to (NGN’s lawyers), but she can provide information on which the defendants may choose to act,” he said.

“There is a benefit to the defendants in her being able to do that near instantaneously in the course of Mr Depp’s cross-examination and, in my view, it would be unfair to the defendants to deprive them of that advantage.”

The rejection is the latest development in a long-running pre-trial conflict between the legal teams of Depp and Heard.

Last week, the high court ruled that Depp had breached an order in the libel case by failing to disclose texts that appear to show him trying to buy drugs. NGN’s legal team asked Nicol to strike out Depp’s claim on the grounds that he had not provided them with the “Australia drugs texts”.

The messages were sent in early 2015, shortly before Heard claims she went through “a three-day ordeal of physical assaults” by Depp in Australia.

In late May, the high court also ruled that evidence from Heard’s former personal assistant can form part of Depp’s case in his claims against NGN and Wootton, after the former employee said she said she had never seen any sign of physical violence, but dismissed evidence from a mechanic who worked for the couple shortly before their divorce.