Liberal MP Warren Entsch has launched an extraordinary attack on Cory Bernardi, saying he is worried by his colleague's ''obsession'' with gay people.

Mr Entsch, a former parliamentary secretary and chief opposition whip, said he cringed when he heard the South Australian senator's latest comments, in a new book and in a television interview on Monday, in which he accused some women of using abortion as ''an abhorrent form of birth control'' and railed against ''non-traditional'' family arrangements such as step-families, single-parent families and same-sex parent families.

Senator Cory Bernardi Credit:Andrew Meares

''He's obviously got an obsession with people that are gay,'' Mr Entsch said. ''It worries me. You've really got to watch out for those that have these obsessions. He who protests the loudest …''