Eight acres of farmland will be used to extend Gilroes Cemetery as planners battle to stop the city running out of space for graves.
But the extra burial land is likely to be filled within six to eight years, prompting Labour councillor John Thomas to make the grim warning at a planning committee last night.
Opposition councillors have now even floated the idea of creating a new graveyard outside the city boundary.
Conservative councillor Andy Bayford said: "Someone from the council should be in touch with (County Council leader) David Parsons, asking if any land is available for the city's use in future."
Leicester City Council plans to use agricultural land it already owns to extend Gilroes, following fears that remaining burial plots will be filled in the next 18 to 24 months.
Scores of objections were received from people living in the nearby Heathley Park estate, and a 280-signature petition was lodged with councillors.
Residents fear their properties will be devalued and have complained that the cemetery extension will prevent people from enjoying green space close to their homes.
Many local Hindus have objected because their holy books say they cannot live near a cemetery. Some have told the council they would have to move house.
Councillor Paul Westley made representations on behalf of residents, saying the development would cause "great offence".
But council officers and some councillors said the concerns were outweighed by the 47 different faiths who should be able to choose to be buried locally.
Labour's Ann Glover said: "Gilroes is the place where the people of Leicester choose to bury their nearest and dearest. It's unfortunate if some people are offended by the extension but that's where people want their loved ones buried."
Lib Dem councillor Parmjit Singh Gill added that the council should have done more to avert the problem.
He said: "We should have seen this problem coming two or three years ago but nothing at all has been done about it."
A motion by Councillor Bayford to defer a decision for a second time was defeated, and councillors voted in favour of the extension by nine to three.
The nearest houses to the site are in Avington Close, Margam Close and Hyde Close but these homes will still be 40 metres away from the proposed cemetery extension. Mature trees and hedges would screen the site, the council said.
Residents and Councillor Hussein Suleman have even cited the Human Rights Act, saying that their right to religious expression would be impeded.
But a council planning report said: "The purpose of the planning system is to regulate the development and use of land in the public interest. It is not to protect the private interests of one person, or a group of people."
Gilroes is the city's main site for burials and cremations and the council says no other suitable sites are available.