Insurance companies have decided to take information being put social networking sites into account when analysing claims.
Research into the online activities of users found that thousands regularly leave themselves open to their homes being raided.
A survey from the Co-operative Insurance of 3,000 has found a third of Britons who use the sites unwittingly put themselves at risk of being burgled.
Some 36 per cent use the sites to update friends on their whereabouts, while 35 per cent count down to events such as holidays, potentially alerting criminals to when their home will be empty.
Separately Legal & General surveyed nearly 3,000 customers and discovered 40 per cent think that location-based social network services such as Foursquare or Facebook are risky as they inform would-be burglars of their whereabouts.
David Neave, of the Co-operative Insurance, said he could envisage a future where claims could be rejected if it was discovered that someone had been reckless with personal information they had posted on a social networking site.
He added it was perfectly possible some insurance companies may in a few years start to monitor the social networking activity of their customers.
"Somebody will do it. That's the nature of the industry we are in," the Daily Mail quoted him as saying.
Experts said burglars could use the online information with published electoral roll data - which is also online - to track down an address.
