Most Underground stations do not have disabled access
Transport for London (TfL) has written off £20m invested in projects that were later cancelled due to its financial difficulties, BBC London has learned.
TfL began installing step-free access at six underground stations in 2009.
It later cancelled the projects after costly preparations because of the impact of the recession.
London Assembly member Caroline Pidgeon said the money was "wasted" but Mayor of London Boris Johnson said the scale of the downturn could not be predicted.
Ms Pidgeon said: "Transport for London have shown incredible incompetence in starting work on step free access at six underground stations and then cancelling the work before its completion.
"Through poor budgeting no improvements in access will take place yet £20m of public money has been totally wasted."
The stations which have had step-free access scrapped are Amersham, Greenford, Ladbroke Grove, Newbury Park, Osterley and West Kensington.
Greenford Station alone had £2.9m spent on cable and drainage work ahead of lift shaft installation before the project was cancelled.
Mr Johnson said: "As part of the package of changes to achieve significant cost reductions, the decision was taken to stop work on six step-free access projects.
"TfL is experiencing a loss in revenue due to the current economic climate which necessitated difficult decisions."
He added: "Given the pressures on TfL's finances, funds were simply not available to us and we had to take the decision to halt the works."