Tony Abbott has forced the resignation of his parliamentary secretary, the right-wing South Australian Senator Cory Bernardi, after Bernardi compared gay marriage to bestiality in the Senate debate over the same-sex marriage bill, and then repeated the comments on radio this morning.

The resignation comes after Malcolm Turnbull (who dismissed Bernardi when he was opposition leader for his attack on rival SA Liberal Christopher Pyne) savaged him, describing his comments as hysterical, alarmist and offensive.