Bendigo and Ballarat's councils have told a Victorian parliamentary probe that UNESCO might require changes to Victoria's planning framework to award world heritage status to sites throughout the region.

The councils are leading a bid by 13 local governments for the status, which would be worth $25 to $66 million a year to the tourism sector, according to some estimates.

Up to 15 historic sites across the region could be nominated. All would have links to Victoria's gold rush, which reshaped the world in the mid-19^th century.

Exactly which ones would be nominated has not yet been decided.

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They would likely include multiple buildings and mining sites, though the councils say they would constitute only a small fraction of land in the region.

A successful bid might have ramifications for parts of Victoria's complex planning system, especially when it comes to areas immediately surrounding any sites awarded world heritage status, Bendigo and Ballarat's council has told the inquiry.

UNESCO could want assurances that any future development in those areas would not diminish the "outstanding universal value" of a world heritage listed site, they said.

The councils suggested "buffer zones" around any successful sites, with new planning rules to protect things like view lines.

Developers in those zones would have to consult communities about heritage matters much earlier.

Currently, "the process for heritage protection is reactionary, triggered very late in development processes and it is often not a priority consideration when planning for change", the councils said.

They suggested communities be asked how new buffer zone developments might impact heritage tourism economies, not just whether any old buildings should be protected.

Buffers could also bring tighter protections for heritage listed places, including new crackdowns on so-called "demolition by neglect".

"Penalties for wrongdoing in respect to heritage are almost invariably too light and not a deterrent to willful action by [a property] owner," the councils said.

The comments came as the National Trust warned parliament that councils needed more guidance if they were to follow through on heritage protection reforms designed to stop demolition by neglect.

Bendigo's council is among those considering whether it can introduce the reforms, but one elected official earlier this year said the state government needed to "come to the party" and give more guidance.

Bendigo and Ballarat's councils told the inquiry its world heritage ideas could also have implications for protections against "over-tourism".

Tourist areas throughout the world are reporting housing shortages because of the number of people renting out buildings for short-term accommodation, the councils said.

Planners in other parts of the world have created zones for short-term accommodation around heritage sites.

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