US actor Scott Bairstow, accused of raping a 12-year-old girl, has pleaded guilty to a reduced charge of second-degree assault, his lawyer has said.

In the modified guilty plea, Bairstow, 33, maintained that he was innocent but conceded that he would probably be convicted if the case went to trial.

Bairstow is due to be sentenced on January 16.

The charge carried a standard sentencing range of three to nine months, Bairstow's lawyer Mark Mestel said.

The actor was originally charged in May with raping the girl, a relative of his wife.

Bairstow has appeared in nine feature films, including The Bone Snatcher, in which he played Dr Zack Straker.