A mother has had access to her young son severely curtailed after she threatened to "cut off his hands'' in an allegedly ``unending struggle for advantage in post-separation politics''.

According to a recent Federal Circuit Court judgment, a bitter seven-year feud between the 11-year-old's parents recently involved the child informing on his father to police for physical abuse under the threat of having both hands severed.

The boy, who wants nothing to do with his mother until he turns 18, told a family consultant his mother took him to the police station and "wrote down a whole bunch of things'' on a note pad.

"She said if I don't say them to the police officer, she'll cut off my hands,'' he said.

Judge Stewart Brown heard allegations of "coaching'' by both parents, but has banned contact between mother and son for six months, with supervised fortnightly visits to resume at the end of the moratorium.

He has not ruled out granting the child's wishes to not see his mother for the next seven years after finding "endemic'' conflict between the parents had left the boy "gravely in risk of education failure''.

Judge Brown said the boy had reported that he was "shocked'' and "scared'' by his mother's threats to cut off his hands and was ``terrified she would actually do it''.

"I am of the view that there is more weight of evidence to indicate (the mother) sought to manipulate her son than is indicative that the father has assaulted the child,'' Judge Brown said.

The boy had declared in a police interview in front of his mother that his father had punched him in the back of the head.

He also alleged at the time that his stepmother had told him his father had given her permission to "bash'' him and she would "enjoy'' it.

The mother had been refusing to hand her son back to the father after a contact visit, based on the abuse claims.

The allegations prompted legal action by the father to get his son back.

The father took the child to police where he retracted the claims and alleged his "mum made me do it''.

The mother voluntarily undertook a psychiatric assessment at the request of the court but no evidence of a psychiatric condition was found.

She has maintained she has a "wonderful relationship'' with her son.

She lost custody of him after school authorities took the stand against her at a parenting trial in 2011, alleging "detrimental emotional influence'' by the mother.

She had been caught photographing her son and other parents and had threatened to hire a private investigator to undertake surveillance at the school.

Judge Brown said his findings against the mother were made with a "heavy heart'', however he could see no end to the conflict.

"After all, in each case, the child has attended the police station with a parent and both (the mother and father) have ample motivation to harbour grudges against the other,'' Judge Brown said.