The block is on the eastern side of the mountain, opposite Emil Madsen Reserve in Wooralla Drive, and straddles Balcombe Creek.

It is also next to Mt Eliza Regional Park, formed after the Moorooduc quarry was abandoned due to flooding in the 1960s and a former Shire of Mornington tip closed.

The block is owned by a group of locals, including some associated with Mt Eliza Football Club, who tipped in $80,000 each in 2006 to meet the $1.6million purchase price.

It had previously been offered to the old Shire of Mornington when it was preparing the regional park master plan in 1992.

Mayor David Gibb said the land, at 185 Wooralla Drive, contained bio-diversity values of state significance and was also recognised by the National Trust for its landscape values as part of the Mt Eliza escarpment. It is the second time the shire has requested the government buy the land, having written to Environment Minister Gavin Jennings in 2008.

"The environmental values of the site are being degraded, despite the shire installing vehicle barriers on the adjoining road reserve," Cr Gibb said.

"The owner of the property has chosen not to fence it and it is being accessed by motorbikes and four-wheel-drives, which are degrading important plant communities and accelerating weed invasion.

"Realising the potential of this site will continue to be comprised until the land is more responsibly managed or brought into public ownership."

Cr Gibb said the shire had asked the government to assess the site's conservation values and reconsider its decision not to purchase the land.

"Purchasing the land in the United Nations International Year of Biodiversity would be a clear demonstration of the government's commitment to the protection and enhancement of biodiversity as set out in the green paper on Land and Biodiversity in a Time of Climate Change," Cr Gibb said.