METRONET bosses insist they are not planning to outsource track and signals maintenance work on the London Underground following accusations by the RMT rail union.
The union is balloting its 1,800 members at the infrastructure company over job cuts, subcontracting plans and a row over pensions.
Metronet is currently in the middle of a job-cutting and reorganisation programme that will see 285 staff made redundant.
And RMT officials are worried that the firm is also planning to contract out more work on the nine Underground routes it maintains under a PPP contract.
General secretary Bob Crow said: 'No sooner had the company taken over the PPP contract than they announced that all f leet maintenance was being sourced to Bombardier.
'Following this was infrastructure and with lifts and escalators now at risk how long before all of signals and track will be outsourced?
'It is our belief that the Metronet reorganisation has been set up to further aid the outsourcing of all major areas of work.
'We believe it is the company's ultimate intention to outsource all the work to other members of the consortium and that Metronet will eventually become a contract organisation.'
Metronet bosses have attacked the union's strike ballot plans as 'completely unwarranted'.
A spokesman said: 'We have made it crystal clear to the RMT that it is our general policy to retain work within our organisation.
'We have already reaffirmed that track and signals maintenance will stay part of Metronet.
'We're reorganising our business to ensure that we can be more effective in delivering our PPP obligations.
'We announced a number of job reductions ? up to 285. More than half of these will be achieved through the release of agency staff and the rest through voluntary redundancy. There are no compulsory redundancies.' The RMT is also balloting 1,500 Tube drivers on taking industrial action short of a strike after London Underground failed to provide assurances that track inspection regimes would be maintained in the event of any action by maintenance staff.
The ballot is due to begin today (Thursday) and end Friday December 2.