In an interview with the Daily Telegraph on Monday, the prince revealed that he had needed counseling almost 20 years after his mother's 1997 death in a car crash.

The 32-year-old admitted he had shut down his emotions and had nearly suffered breakdowns, eventually taking the advice of older brother Prince William that he should seek help.

Harry, who served in the British Army for 10 years, said he had taken up boxing to deal with his aggression after feeling he was "on the verge of punching someone."

The prince, who launched the "Heads Together" mental health campaign alongside William and sister-in-law Kate, Duchess of Cambridge, told interviewer Bryony Gordon he did not process his grief until he was in his late 20s.

"My way of dealing with it was sticking my head in the sand, refusing to ever think about my mum, because why would that help?"

'Grief came to the forefront'

The suppression of grief eventually led to "two years of total chaos," he said, forcing him to face his problems head on and seek counseling.

"All of a sudden, all of this grief that I have never processed started to come to the forefront and I was like, there is actually a lot of stuff here that I need to deal with," said the royal, who is fifth in line to the throne.

Harry has never spoken publicly about his problems with grief, in part because of a wariness of the British press. Paparazzi photographers shadowed the every move of Harry and William's mother - even being blamed by some for causing the crash in a Paris tunnel that killed her. Diana, known for her sartorial elegance, was married to heir-to-the-throne Prince Charles between 1981 and 1996, when the pair divorced.

Praise for candid words

In their work with the Heads Together campaign, the young royals have argued that mental health problems must be treated as seriously as other illnesses and that people should feel more able to talk about them openly and without stigma.

Harry, who also works with wounded veterans, told Gordon he was in a "good place" now.

Harry's openness was praised by British mental health charity Mind, which described the interview as a "turning point."

"It's inspiring to see Prince Harry speaking out about his experience. It shows how far we have come in changing public attitudes to mental health that someone so high-profile can open up," said Mind chief executive Paul Farmer.