Almost a third of Americans have received naked picture message

While 16 per cent have broken up with someone via text.

Marketing network Euro RSCG's annual Valentine's Day survey examines the sex lives of social networking Americans to find 49 per cent started a relationship online, while almost a fifth have had a sexual encounter.

Results show 69 per cent say the internet has made it easier for people to cheat on their partners, which has become even easier as smartphones allow constant access to the web while on the move.

Facebook now has over 425 million mobile users, while Twitter has around 60 million monthly active mobile users, and the two social networks both have a number of kinky subscribers.

The report says that 42 per cent of active tweeters consider themselves to be 'sexually adventurous', compared to a third of Facebookers. Meanwhile, over half of tweeters 'have sex at least once a week', against 46 per cent of Facebookers.

Additionally, more than a quarter of tweeters and 16 per cent of Facebookers believe they masturbate more thank anyone they know, while 21 per cent of tweeters worry their sexual fantasies aren't normal.