Members of Amicus embarked on industrial action last week in protest at what they claim are attacks on pay and conditions.
The union said Fujitsu was imposing two different pay deals on its workforce in Manchester, delaying pay rises and offering no increase in pay rates for many lower paid jobs. Amicus also said that Fujitsu were attempting to deny union recognition and cutting employee severance terms.
Amicus called on the company to resume talks through the arbitration service ACAS. Fujitsu refused to comment.
