Princess Diana's sons speak of shock over mother's death

Both the sons of Princess Diana have opened up about the shock and the mental trauma they faced after losing their mother in a tragic car crash in Paris in 1997.

Days after Prince Harry revealed that he had to undergo counselling to help come to terms with their mother's death, his older brother said that the shock of losing his mother is still with him, 20 years after she was killed.

The 34-year-old Duke of Cambridge revealed in a new BBC documentary to be aired tomorrow that the shock "never leaves you".

"I still have shock within me - people say it can't last that long but it does," he told the 'Mind over Marathon' documentary, made to promote his support for mental health charities in the UK.

The second in line to the British throne told the BBC that he had to "learn to deal with" the loss of a parent.

"The shock is the biggest thing (which) I still feel 20 years later, about my mother. You never get over it, it's such an unbelievably big moment in your life that it never leaves you. You just learn to deal with it," William said.

William said he wants people to speak more openly about mental health.

Earlier this week, he had said it was time to end the British stiff upper lip culture of bottling up grief.

In the two-part documentary, William speaks to a group of 10 runners living with or affected by different mental health issues, as they prepare for the start of the annual London Marathon on Sunday.

On Monday, Harry had said that he had to "shut down all his emotions" for almost two decades after losing his mother, Diana, Princess of Wales.

Disclosing that he has spoken to a professional about his mental health, the 32-year-old described how he only began to address his grief when he was 28 after feeling "on the verge of punching someone" and facing anxiety during royal engagements.

(This article has not been edited by DNA's editorial team and is auto-generated from an agency feed.)