Macaulay Culkin has opened up about his father, describing him as as "monster".

The former child actor shared that his Uncle Buck co-star John Candy was a welcome support, explaining the late comedian was one of the few to notice something may have been amiss in Macaulay's home life.

Macaulay said his father, Kit Culkin, had been "difficult" during the shooting of the 1989 hit comedy, but that his abusive behaviour escalated when Macaulay's fame skyrocketed after 1990's Home Alone.

"Listen, even before the wave crested and the Home Alone stuff was happening, it was not hard to see how difficult my father was," Macaulay, 45, shared in new documentary John Candy: I Like Me. "It was no secret. He was already a monster. All of a sudden, the fame and the money came, and he became an infamous monster. He was already not a good guy."

He described John, who died after a heart attack in 1994 at the age of 43, checking in with him after the success of Home Alone.

"I think John was looking a little side-eyed, like, 'Is everything alright over there? You doing good? Good day? Everything's alright? Everything good at home? Alright'," Macaulay remembered.

Macaulay is estranged from his 80-year-old father and previously described him as "mentally and physically" abusive.