It can seem a laugh at the time, but be careful. That excruciating clip filmed by your drunken mates can return to haunt you.

British firms are increasingly following American companies in using the internet to dig up “digital dirt” on potential future employees.

In March, in a poll of 500 employers by Poolia, recruitment agency two thirds admitted regularly carrying out internet searches, including checking social networking sites such as MySpace, Facebook and YouTube. An even larger poll, of 2,000 workers and 600 employers, by the social networking site Viadeo suggested that one organisation in five carries out such checks — and that a quarter of those that did had rejected applicants as a result.

Common internet reputation — or “NetRep” — black marks cited in the poll included “alcohol abuse”, showing a lack of respect for your job, or that the candidate was “personally into some activities that did not fit ethically into the company”.

So far as she is aware, Helen Simmons, a 25-year-old London PA in financial services, has never been vetted online by an employer and makes clear that she would have nothing to hide in any case. Nevertheless, she has taken steps to ensure that her online personal life remains private. “I had a MySpace and a Facebook account but because of all these stories I’ve closed them,” she says. “A lot of my friends are worried about this, too. People are closing accounts or making them private so that only friends can access them.”

But it’s not a one-way street. Helen has “googled” employers to whom she has applied. “I look for anything that might put me off — high staff turnover, for instance,” she says. “I’ll also see if there are any blogs on them. If I’d been offered an interview and found something off-putting, it would stay at the back of my mind.”

Companies should be wary, says Shaun Greenfield, sales director at Poolia. “You’d have to be very careful about rejecting someone because of something posted online, particularly if it related to age, religion or sexual orientation.”

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