Local communities could find it harder to fend off coal seam gas mining and exploration applications under a controversial law being introduced by the Napthine government.

An overhaul of Victoria's mineral laws quietly unveiled in Parliament last week will make it impossible for local communities to apply for mining exemptions without the area first being assessed for its mining potential.

Energy Minister Nick Kotsiras told Parliament the Mineral Resources Act was being changed so potentially valuable mining deposits - including coal seam gas - are not ruled out for development without a valuation.

''This will provide greater consideration of mineral resources before precluding potentially mineral-rich land from future development,'' he said.

The move comes as the Gippsland communities of Poowong, Harmers Haven and Seaspray - which have declared themselves ''coal and coal seam gas free'' - prepare to use Victoria's current laws to apply for exclusion zones to head off mining development.