One third of people stalk their former lovers on Facebook and Twitter, and one in five do so with their current partner's ex, according to a new study.

Researchers said that even if you are happily settled in a relationship you might not be totally safe from your current partner's prying eyes.

Around seven per cent of people admitted they have experienced the stomach-flipping horror of a bitter ex threatening to post a racy photograph on-line, the 'Daily Mail' reported.

The survey also found that more than 50 per cent of adults share their email password, social media log-ins and bank card pin numbers with their partners, and 42 per cent people in UK admit checking their partner's inboxes.

Despite this lack of complete privacy when it comes to technology, 54 per cent of people in the UK admit to having personal or intimate texts, emails or photos stored on their phone.

Researchers found more than a third of adults will send intimate or romantic images via email, text or social media on Valentine's Day.

The survey of more than 1000 British adults by McAfee and MSI International also discovered that "what's mine is yours" mentality towards sharing intimate content on-line can backfire when relationships break down. A quarter of respondents said that they regret sending intimate photos to an ex.

"We're a trusting bunch when it comes to sharing personal content with our nearest and dearest, but it's important to remember the potential repercussions if things go wrong," warns Raj Samani, EMEA CTO, McAfee.

"People should keep passwords and pins to themselves and think twice before posting personal information to social media.

"Sending a cheeky Valentine's Day message is all part of the fun, but simple precautions can ensure that those intimate images remain private," Samani said.