Within hours of the deal with Tube contractor owners Bechtel and Amey, transport union RMT threatened industrial action if any of Tube Lines 3,000 strong workforce is axed.
TfL said that its first priority is to complete the upgrade of the Jubilee Line after ending the Public Private Partnership on the Tube network.
From June, TfL will carry out the huge upgrade in-house and maintains it will not ask for extra financial help from the government, taxpayers or commuters.
London Underground intends to take a “revised approach”, aiming for a less disruptive upgrade programme on the Northern Line.
Maintenance company Tube Lines was responsible for the Jubilee, Northern and Piccadilly lines.
Union leaders have warned of industrial action unless assurances over jobs are given following the dramatic return of maintenance work on London Underground to the public sector.
Rail Maritime and Transport union general secretary, Bob Crow, said: “If the reports are true that Tube Lines is at last being taken back under public control it would be a welcome development and would kill off the privatisation disaster on the tube once and for all.
“This will be a recognition on a massive scale that transport privatisation does not work and RMT’s campaign to roll out the renationalisation of the rail network will continue regardless of who forms the next government.”
The takeover follows the collapse of Metronet in 2007, the maintenance company responsible for two-thirds of the Tube, whose staff now work for TfL.