The opening day of Prince Harry's damages battle against the owners of The Sun newspaper has been delayed after it emerged that the two sides are involved in potential settlement talks after years of legal warfare.

The duke's lawyers were due on Tuesday to open an eight-week trial of his allegations that journalists at News Group Newspapers used unlawful techniques to pry into his private life - and executives then allegedly covered it up.

Moments before they were to begin presenting their case, they asked for an adjournment.

However, after hours of secret discussions, and no sign of a final agreement that could change the nature of the trial, the judge demanded that the two sides begin - leading them both to say they would ask the Court of Appeal to overturn that order.

The practical effect of their objection is that the case has been delayed until at least 10 am on Wednesday - which means both sides have more time to negotiate.

It's not clear what has been raised in the 11th-hour negotiations.

Prince Harry has repeatedly said he wants a trial so that he can get "accountability" for other alleged victims of unlawful newsgathering of private information by NGN journalists.

NGN has denied there was any wrongdoing at The Sun or that executives across the group covered it up.

The Rupert Murdoch-owned empire has long admitted that journalists at the News of the World, which closed down in 2011, did use unlawful techniques but has always denied that it was widespread.

This morning, lawyers for Prince Harry and former Labour MP Lord Tom Watson, the other remaining claimant, asked Mr Justice Fancourt to delay opening the case twice - meaning the court did not sit until 2 pm.

David Sherborne, Prince Harry's barrister, said there was potentially a "good prospect" of an agreement that would save the court time.

"We are very close, there is an issue with time and gaining instructions," he said.

"It is not the only factor."

Anthony Hudson KC, for News Group Newspapers, added the parties needed more time because of "time differences" and said that both parties were involved in a "settlement dynamic".

Mr Justice Fancourt - who has repeatedly criticised both sides for long delays and spats over how the case should be conducted - refused to give them more time, saying that the case should start, even if there were still talks behind the scenes that could change the nature of the trial.

"I am not persuaded that if there is a real will to settle this it could not have been done by today," said the judge.

News Group Newspapers' lawyers then asked for the court to sit in private - without the presence of the media - to hear more about what was going on.

The judge refused, saying he was not going to sit in "secret" - and then both Prince Harry's team and NGN's lawyers said they would ask senior judges to overturn the order to get underway.