Trade union Unite has accused Fujitsu of running a 'two-tier' redundancy policy for offering some employees 90 days' consultation and others just 30 days.
It comes as the IT company announced 93 job cuts.
If there are fewer than 100 redundancies, the statutory minimum consultation period is just 30 days, which is what some Fujitsu staff will have.
However, some of the affected staff, including those at Fujitsu's offices in Manchester, are covered by a union-negotiated Security of Employment Agreement that guarantees them at least 90 days' consultation before redundancy.
Unite is demanding that Fujitsu makes the redundancy consultation period equal for all at 90 days.
"Fujitsu must end its unfair policy of allowing a two-tier workforce to exist when it comes to redundancies. Fujitsu is profitable and can afford to deal with any job losses through a fair, high-quality process for all workers.
"Consistency is not too much to ask for. We are demanding that Fujitsu acts and gives all its staff the same opportunity to protect their jobs, or find alternative employment in the company where possible," said Kevin O'Gallagher, Unite national officer.
A spokesperson for Fujitsu said: "Fujitsu operates in line with all current legislation in this area and is working closely with affected staff to ensure this difficult situation is managed appropriately and professionally."