Opposition Leader Peter Dutton says a Coalition government would hold a second referendum on recognition of Indigenous Australians if the Voice to parliament fails next month, promising a symbolic mention of the nation’s first people in the Constitution.

The plan – immediately dismissed by prominent Yes campaigners as “another Canberra-based idea by a Canberra-based politician” – would send voters back to the polls to vote on recognising Aboriginal and Torres Strait Islanders, but without any new advisory body created.