A narrow majority of Australians want a republic with support highest among younger and middle-aged Aussies, a new poll shows.

The survey, released as Prince Harry and his new wife Meghan arrive for their first tour of Australia, shows all age groups believe the nation should become a republic with an Australian head of state.

The independent poll of 1000 Australians, commissioned by the Australian Republic Movement, found 52.4 per cent want a republic.

Of those polled, 25.2 per cent weren't sure of the need for change, with 22.4 per cent against or strongly against a future as a republic.

AAP

The ResearchNow poll gauged the views of Australians aged 18 to 65 and older.

In all age groups more people agreed than disagreed on the need for change.

Support was strongest among 25-34 year olds, at 58.6 per cent but Australians aged 45-54 weren't far behind at 57.9 per cent.

It was lowest among Australians aged 65 and older, but even then almost half (47.5 per cent) agreed or strongly agreed that the nation should become a republic with an Australian head of state.