John Howard has urged Prime Minister Malcolm Turnbull to make changes to the Racial Discrimination Act to protect free speech while pursuing economic reform saying 'you can walk and chew gum at the same time'.

Former prime minister also called on Mr Turnbull to put significant changes to Australia's taxation and workplace relations systems back on the agenda, even if they seem unpopular with the public.

Former prime minister John Howard. Credit:Andrew Meares

Speaking on Sky News on Sunday, Mr Howard acknowledged he had not tried to amend section 18C of the act - which prohibits speech that offends, insults, humiliates or intimidates on the basis of race - when he was prime minister because it had been "dormant" and "didn't seem to matter".

"Once the Andrew Bolt case came about we knew the thing had potency," he said.