Work on Crossrail- the biggest project since the Channel Tunnel - is not cut
A union leader has described a plan by Transport for London (TfL) to cut £2.4bn from its budget as "bad news for Londoners" and has demanded talks.
Transport Salaried Staffs Association General Secretary Gerry Docherty said there would be "significant" job cuts.
TfL said the savings would come about through "delivering management, eliminating duplication, reducing headcount and improving technology."
They promised consultation with unions over the plans announced last month.
TfL wants to save the cash over the next 10 years.
A TfL statement said: "Transport for London's 10-year business plan sets out how billions of pounds are being invested to improve the capital's transport system by focusing on the upgrade of the Tube, building Crossrail, launching a cycling revolution and through smoothing traffic flow across London.
"The changes are focused on support and non-operational functions in order that we continue to improve our passenger services whilst we deliver this massive investment programme.
"Much of this will be achieved by not filling vacancies.
"However, our investment programme, particularly Crossrail, will also see the creation of thousands of skilled jobs in many different roles."