Stonnington Council is set to take a landmark vote on a controversial policy that could compel hundreds of home owners and businesses to sell their properties to the city for conversion into parks.

But nearly all owners are being left in the dark about whose properties have been selected, with the council choosing not to publicly release the list of 450 identified sites in South Yarra, Toorak, Armadale, Glen Iris, Prahran and Malvern.

In the first stage of its strategy, the council will decide on Monday whether to apply a new planning control – known as a Public Acquisition Overlay – to five privately owned properties in Prahran, marking them permanently ‘‘reserved’’ as potential public space. The designation gives the council the option of buying the land at some future date.

The Prahran properties are among hundreds of private and publicly owned sites identified in a confidential report commissioned by the council, which is looking to reverse the decline in the amount of open space available in the municipality after years of intense development.

But the policy is bitterly resented by some land owners, who claim they will be left in ‘‘limbo’’ by a government that is laying a claim to their land but has made no formal commitment to buy it.