The Napthine government has introduced sweeping changes to Victoria's national parks allowing for 99-year private leases - in the same week Canberra is considering expanding its powers over the parks.

The state changes mean the historic Point Nepean Quarantine Station is in effect up for sale, according to activist Kate Baillieu.

The commercial real estate section of The Saturday Age carried an advertisement from real estate agents Jones Lang LaSalle to lease the Quarantine Station. The government has also asked for expressions of interest for private development of the 17-hectare site.

Matt Ruchel, executive director of the Victorian National Parks Association, said the new 99-year leases that will apply in all of Victoria's national parks, including Wilsons Promontory, were deeply concerning. ''National parks are primarily for conservation, not development,'' he said.

Environment Minister Ryan Smith said the 99-year leases would ''give investors greater certainty and a stronger incentive to develop innovative, high-quality proposals in our national parks''.