Shell has been accused of keeping IT staff in the dark over their future following the oil giant's £4bn outsourcing deals.
EDS will be the operational integrator for the outsourcing contracts, with approximately 1,500 Shell IT staff and contractors to join EDS, spread throughout 65 countries; about 900 Shell staff transferring to T-Systems and 560 to AT&T.
The trade union Unite says anxiety levels are running high among the fewer than 200 UK tech staff who will be transferred to either AT&T, EDS or T-Systems under the five-year deals to outsource Shell's IT infrastructure.
Regional union officer Graham Tran said there has been no communication to staff about who will be transferred to the outsourcers or made redundant from July.
He said: "It is a very worrying time for the staff. This is poor, they [Shell] should not dump the workers in the fashion they are doing."
Those Shell tech staff who will be transferred across to either AT&T, EDS or T-Systems will be given a number of options.
The transferring staff will be offered a better financial package than the statutory minimum but the union claims this is still just a "halfway measure" and "below the expectations of the membership".
Transferred Shell staff will not retain their existing employment contract rights and redundancy packages under their new employers, with Shell estimating existing rights will expire after about two years.
Tran said: "Shell are not committed to the UK. This is part of a mass exodus and quite frankly the sooner they go the better."
Shell has stressed there will be up to 30 redundancies at worst among the 2,960 tech staff who will be affected by the deal globally.
A Shell spokesman said: "Shell's IT staff have been consulted over a long period on this issue and the impact of the [deal] was confirmed to all staff. The relevant staff councils have been fully involved and have said they are fully satisfied with the process."