Oscar winner Mo'Nique's brother says he molested the actress when they were children and wants to apologise to her.

Gerald Imes said on The Oprah Winfrey Show on Monday he was 13 when the sexual assault occurred and Mo'Nique was seven or eight.

Abused as a child ... Mo'Nique celebrates winning the Best Supporting Actress award at the Oscars for Precious: based on the novel Push by Sapphire. Credit:Getty Images

Imes says he decided to appear on Oprah to apologise to Mo'Nique and "bring back some family unity".

Mo'Nique has discussed her brother's molestation in previous interviews.