Penis enlargements have become one of the 'most hyped' ops

Surgeons at St Peter's Andrology Centre in London quizzed 42 men who underwent operations, the European Urology journal reported.

The average increase was 1.3cms (0.5in), but two thirds said they were unhappy with the results.

Experts said spam e-mails and advertising were giving men unrealistic expectations about penis surgery.

Research should be directed toward non-surgical options

Yoram Vardi, of the Rambam Medical Centre in Israel

Report author Nim Christopher, a urologist at St Peter's Andrology Centre, said penis enlargements had become one of the "most hyped" operations because of the incessant bombardment of e-mail accounts and websites with spam advertising.

"For patients with psychological concern about the size of the penis - particularly if it is normal size - there is little point in offering them surgery because it makes no difference," he added.

He said men often requested another bout of surgery because of their dissatisfaction.

The study said rather than having surgery the men should be referred for psychological counselling.

Other experts agreed it should be a last resort.

Yoram Vardi, of the Rambam Medical Centre in Israel, said: "We now know that the majority of these patients are dissatisfied after these procedures. Research should be directed toward non-surgical options."