Employers and universities shopuld not be making decisions about applicants based on information on social networking sites and blogs, an internet expert has said.

Applicants should not be judged on information that they do not intend to submit for professional purposes, according to John Carr, chairman of the UK Children's Charities' Coalition on Internet Safety.

And any organisation doing so could be infringing privacy, he said.

"It's like reading someone's diary. If employers or universities are searching social networking sites and blogs and using the information to make decision, at the very least it's unethical and underhand. It could even be illegal," said Carr.

But according to the Uk data protection watchdog, looking at the information that someone has made public would not be illegal.

"It wouldn't be a breach of data protection to look at it, but if a company decided that it didn't like the look of someone, based on which region they are from, for example, there may be some employment legislation that could be breached," said a spokeswoman for the Information Commissioner's Office.