Video report by ITV News Royal Editor Chris Ship
A source close to Prince Harry said suggestions in the press to the contrary were attempts to "drive a wedge between" Harry and his brother the Duke of Cambridge.
The source said: "Harry is getting regular updates and is aware of everything that is happening.
"You do not need a public statement to imagine how he is feeling privately, people know how much his mother means to him."
The source added: "He has bravely spoken out in the past about loss and grief, and the immense impact it has had on him.
"Sadly, some people are not just seeing this as a drive for truth, but also trying to use this as an opportunity to try to drive a wedge between the brothers."
Earlier this week William publicly welcomed the investigation into Martin Bashir’s interview with Princess Diana, describing it as a “step in the right direction”.
It comes as Diana's brother, Earl Spencer, revealed he is "not at all satisfied" with the parameters of the inquiry.
He has previously alleged he was shown 'false bank statements' by interviewer Martin Bashir ahead of Diana’s interview with Panorama, and they were used to help the reporter gain access to the princess.
The BBC has appointed a retired judge, Lord Dyson, former master of the rolls, to lead an investigation into the Diana interview.
But on Friday, Earl Spencer questioned the scope of the probe.
He tweeted: “As I’ve told the BBC this evening, I’m not at all satisfied with the parameters they’ve set around their enquiry into the @BBCPanorama interview with Diana of 25 years ago tonight.
“Lord Dyson must be free to examine every aspect of this matter, from 1995 to today, as he sees fit.”
The investigation will consider if the steps taken by the BBC and Bashir were appropriate and to what extent those actions influenced Diana’s decision to give an interview.
It will also examine what knowledge the BBC had in 1995 and 1996 of “mocked up bank statements purporting to show payments to a former employee of Earl Spencer (and) the purported payments to members of the Royal Households”, the corporation said.
The BBC says Diana had written a note saying she did not see the false bank statements and they played no part in her decision to give the interview.
On Thursday, TV watchdog Ofcom said it will not launch its own investigation into the BBC Panorama controversy, but will follow the independent inquiry “closely”.
The BBC has insisted that investigation has a sufficiently broad scope.
A spokesman for the corporation said: “The review is fully independent and the terms are suitably broad and wide-ranging.
“We hope that everyone will support Lord Dyson’s work in establishing the truth.”
The Duke of Cambridge has welcomed the investigation, saying it "should help establish the truth behind the actions" that led to the programme.
The BBC said Bashir, who is now its religion editor, is currently signed off from work, recovering from quadruple heart bypass surgery with significant complications from having contracted Covid-19 earlier in the year.
The princess sent shockwaves through the monarchy with the interview, which included candid details about her marriage and the Prince of Wales’s rumoured relationship with Camilla Parker-Bowles, his now wife.
The explosive Panorama interview famously featured Diana saying: "Well, there were three of us in this marriage, so it was a bit crowded."
Diana also questioned Charles’s suitability as king.
A month later, the Queen urged the separated couple to divorce, which they did in 1996, a year before she died in a car crash in Paris.