Crossbench warned to reject Heydon motion

The federal government has written to crossbench senators urging them not to back a Labor motion that asks the governor-general to sack royal commissioner Dyson Heydon.

Labor plans to ask the Senate to back its move after Mr Heydon rejected union arguments he disqualify himself from overseeing an inquiry into trade union corruption because he planned to address a Liberal Party event.

Government Senate leader Eric Abetz warned the move risks encroaching on the separation of powers and, in any event, would have no legal effect.