Johnny Cash's daughter KATHY is distraught after viewing new Cash biopic Walk the Line, because it portrays her mother as a "mad little psycho".

Kathy praised Joaquin Phoenix and Reese Witherspoon's performances as her father and his second wife JUNE CARTER CASH, but insists the portrayal of her mother Vivian Liberto Distin was wholly inaccurate.

She says, "My mom was basically a nonentity in the entire film except for the mad little psycho who hated his career. That's not true. She loved his career and was proud of him until he started taking drugs and stopped coming home."

But Kathy's half-brother JOHN, whose mother was June Carter Cash, insists he never intended to marginalise his father's first wife: "I'm compassionately understanding, (but) the point of the film is my parents' love affair."