Sydney, Aug 31 - Online therapy to treat common mental disorders is just as effective as visiting a psychotherapist in person, says a new study.

Anxiety, social phobias and depression are conditions that respond well to clinician-supported internet-based treatments with participants recording recovery rates comparable to those in face-to-face therapy.

Moreover, the online sessions were significantly more cost-effective than traditional treatments and required as little as a quarter of time.

'In the Shyness Program 85 percent of participants recorded good improvement in their scores on measures of social phobia, and more than a third of depressed patients no longer met the criteria to be diagnosed as clinically depressed,' said Nick Titov, study co-author.

He conducted the studies with Gavin Andrews from University of New South Wales (UNSW) School of Psychiatry and The Virtual Clinic at the St Vincent's Hospital here.