Buenos Aires (AFP) - An Argentine appeals court has touched off protests by reducing the sentence of a man convicted of abusing a six-year-old boy, on grounds that the victim was a homosexual who had previously been abused by his father.

The Federation of Gays, Lesbians, Bisexuals and Transsexuals on Monday called for impeachment trials of the two members of a Buenos Aires appeals court who signed the decision.

The judges -- Horacio Piombo and Benjamin Sal Llargues -- slashed Mario Tolosa's prison sentence from six years to three years and two months in a ruling disclosed on Monday.

Tolosa, the vice president of a neighborhood soccer club, had been convicted of abusing the boy in 2011.

In reducing Tolosa's sentence, the judges reasoned that the boy, having been previously abused by his father, could not have been sexually abused in the same way a second time.

The judges added that "it is clear that the sexual choice of the minor ... would already have been made."

They contended, without any basis, that the child had made "a precocious choice of that sexuality."

In a radio interview Monday, Piombo defended the ruling, arguing that there were no aggravating circumstances "because the victim experienced the situation previously with another victimizer."

"The aggravated abuse occurred when the father initiated him in the aberrant" behavior, Piombo said.

Prosecutors appealed the judges' decision as "perverse and irrational."