City planners say they have been left with little power to haggle for desperately needed affordable housing because high-rise developers are already getting what they want.

Melbourne City Council experts want "bonuses" to be given to those that build subsidised apartments, in a scenario that could see authorities trade off extra tower height for community benefit.

But the policy is likely to fail in established city suburbs because current discretionary height controls are often not enforced by Victoria's planning minister, responsible for approving Melbourne's tallest towers.

"Given the lack of strong height or density controls within the municipality, particularly within the capital city zone, there are currently only limited areas where development bonuses could work," the council's recently released Homes for People Housing Strategy said.

The council will aim to create 1721 new affordable homes in the inner-city by 2021, in the plan likely to be endorsed by councillors next week.