People who spend a lot of time surfing the internet are more likely to show signs of depression, British scientists said today. But it is not clear whether the internet causes depression or whether depressed people are drawn to it.

Psychologists from Leeds University found what they said was "striking" evidence that some avid net users develop compulsive internet habits in which they replace real-life social interaction with online chat rooms and social networking sites.

"This study reinforces the public speculation that over-engaging in websites that serve to replace normal social function might be linked to psychological disorders like depression and addiction," the study's lead author, Catriona Morrison, wrote in the journal Psychopathology.