A US politician wants to force convicted sex offenders to pay for their own surgical castration.

Steve Hurst, an Alabama state representative, has introduced a bill that would mean all sex offenders over the age of 21 have to fund the procedure before being released.

The politician has been pushing for near identical legislation with similar bills seven times since 2006.

Mr Hurst said: "I've often wondered what that child went through, physically and mentally, and what kind of shape he's in now

"They (sex offenders) have marked these children for life. They will never get over it. And if they've marked children for life, they need to be marked for life.

"Some people have said it's inhumane. But what's more inhumane than molesting a child?"

Although no states have surgical castration laws, a number already have legislation requiring chemical or voluntary surgical castration.

Chemical castrations allow sex offenders to receive regular injections of a drug that lowers testosterone to pre-puberty levels and reduces their libido.

The civil rights group, the American Civil Liberties Union, state that castration is a "cruel and unusual punishment."

The founder of a sexual disorders clinic at John Hopkins University, Dr Frederick Berlin said lowering testosterone levels does reduce libido and sexual urges.

But he added many sex offences are not sexually motivated.

Dr Berlin said: "There are many sex offenders who aren't driven by intense sexual urges.

"Some of these folks have other mental health issues, so it could just lull us into a false sense of security. Just to do it as a one-glove-fits-all is very unlikely to be helpful."