Image copyright Kansas Department of Corrections

A US judge has found that two girls, aged 13 and 14, were partly to blame in a sex abuse case involving a 67-year-old man - and reduced his sentence.

County District Judge Michael Gibbens said "the victims in this case, in particular, were more an aggressor than a participant in the criminal conduct".

He reduced the sentence of Raymond Soden, who was convicted last year.

Prosecutors are considering an appeal. A child rights group said the girls were the victims, not the aggressors.

Soden was sentenced to five years and 10 months in prison, less than the minimum of 13 years called for by Kansas sentencing guidelines.

The judge said the girls went to Soden's house voluntarily and had taken money for sexual favours.

"They were certainly selling things monetarily that it's against the law for even an adult to sell."

But Michelle Herman, president and CEO of Sunflower House, said "sexual assault is never the victim's fault".

"It doesn't matter what the girls did or didn't do, he is still the adult and nobody deserves to be taken advantage of sexually," Ms Herman was quoted as telling the Kansas City Star.