Fifi Geldof's depression hit her ''full whack'' following the death of her sister Peaches.

The 31 year old - who is the eldest daughter of Bob Geldof and the late Paula Yates - admits she has been able to ''mask'' the condition for some years but her problems have worsened since her 25-year-old sibling died of a drug overdose in April.

Writing on her Instagram account, Fifi said: ''I wear a permanent mask so I won't feel judged for feeling how I actually feel.

''You can't escape it, it just simmers under the surface when it's not hitting you full-whack.

''Which, for obvious reasons, it has done to me for the last few months.

''People wouldn't have the first clue of it to look at me or talk to me, though.''

Fifi's comments come just weeks after the inquest into Peaches' death found that the TV presenter - who was found on a bed surrounded by drugs paraphernalia - had died as a result of a heroin overdose.

The PR executive - who also has sisters Pixie and Tiger Lily - also felt the need to speak out following the news that 'Mrs. Doubtfire' actor Robin Williams took his own life earlier this week due to his struggle with depression.

She wrote: ''Devastated by the news. Depression needs to be taken a lot more seriously.

''No one should feel pushed to those actions by their all-encompassing misery.

''Makes me so sad that he had the world crying with laughter whilst drowning in his own tears.''

Fifi added: ''I think this has prompted me to want to speak out publicly about my own depression which I've suffered from for years.

''Just in a feeble attempt to bring some more awareness and understanding to something that oughtn't to be surrounded by such a stigma.''