The future location of Chislehurst Library is uncertain after Bromley Council put the freehold up for sale.
The council is inviting developers who are interested in acquiring the site - including car park - in Red Hill.
The announcement comes amidst the council's reduction of £300,000 in the 2014/15 budget for the library service.
A replacement for Chislehurst library would need to be provided by developers to the council's standards.
Alison Stammers, chairman of the Chislehurst Town Team, said: "We are delighted that it is a condition that an alternative library facility is to be provided.
"The library is extremely well used, the future of the library is very important.
"We will be watching this incredibly closely as well as any subsequent planning applications."
The future could see either a commercial or residential development on site.
If commercial, the council would consider the first floor being the new home for the library.
If residential, a new location would need to be found, but the council stipulated it would have to be: "At least as accessible and prominent as the current location and would be subject to the approval of the Council."
A temporary facility would need to be found during any construction period.
The developer will be responsible for this, selecting a site subject to the council's approval.
The council recently ran a public consultation on proposals to hand over management of six libraries to external providers, which ended on February 2.
Control would pass to local volunteer or social enterprise groups under the plans.
The remainder would come under scrutiny by the council to see if they could outsource management.
But Roisin Robertson, Green Party candidate for Bromley and Chislehurst, said: "Their proposals to leave less-affluent areas with un-funded, un-supported community-run Libraries would appear to fly in the face of public opinion and public support.
"I maintain the position that all Libraries should remain within the public funding and control of the elected Council."
Bromley's mobile library service was axed in September last year due to financial pressures.
The Priory building, home the borough’s museum, is also planned to be sold.
The closing date for offers for Chislehurst Library is April 22nd.
To view the proposals visit: bromley.gov.uk/downloads/file/2142/chislehurst_library_and_car_park_sales_particulars