The men, 91 of whom are circumcised, were subjected to touch-sensitivity tests where a standardised instrument was pressed onto 17 different places on their penises with calibrated monofilaments. The men could not see where they were being touched.

Researcher Dr. Morris Sorrells and his team also found that the region most sensitive to fine touch on the circumcised penis was the circumcision scar, and the glans of the circumcised penis is less sensitive to fine touch than the glans of the uncircumcised penis. The transitional region from the external to the internal prepuce is found to be the most sensitive region of the uncircumcised penis and more sensitive than the most sensitive region of the circumcised penis.

The researchers did not find interaction between age and circumcision status.

Sorrells said: "The most sensitive part of the penis is the preputial opening. The results confirmed that the frenulum and ridged band of the inner foreskin are highly erogenous structures that are routinely removed by circumcision, leaving the penis with one-fourth the fine-touch sensitivity it originally possessed."

The results of the study contradict an one conducted in 1966 by Masters and Johnson in which found no difference between circumcised and intact penises. The study has been said to be insufficiently documented and did not take into account the role and function of the foreskin.

The National Organization of Circumcision Information Resource Centers; an educational non-profit organisation which opposes genital cutting of male, female, and intersex infants and children; welcomed the findings.

"We've had anecdotal evidence of a significant loss of sensitivity from circumcision for a long time. Now we have proof," director Marilyn Milos said.

"More work needs to be done. We need to know how this translates into sexual functioning and sexual pleasure. Many circumcised men say they couldn't stand any more sensitivity, but intact men obviously can stand it, so it's a matter of quality as well as quantity. The bottom line is, circumcision takes away sensitivity, which translates into a loss of pleasure, too."

Published in the April 2007 edition of BJU International (the former British Journal of Urology) under the title "Fine-Touch Pressure Thresholds in the Adult Penis," the study can be read on www.icgi.org.