Snapchat is being hijacked by middle-aged people, new data shows, as experts warn it is set to to become a playground for secret affairs.

The combination of Snapchat's ageing demographic and its "disposable" messaging system mean it now is an ideal tool being discovered by middle-aged people who want to hide communication with their lover from their husband or wife, experts said.

The app lets users send each other short videos and photos, or "snaps", which are automatically deleted after a single viewing, meaning they are less likely to be discovered by a snooping partner.

Last year the number of 45 to 54 year olds using Snapchat in the US increased by 34 per cent from 3.4 million to 4.7 million, data from technology analyst firm eMarketeers shows.