"While senior managers are pocketing bonuses in excess of what some of our members earn in a year, it's not only wrong, it's offensive for Fujitsu to claim it can't afford to increase pay.

"Just because these staff are off the government's books, ministers are ultimately responsible for what happens in their department's name and cannot simply wash their hands of issues like low pay among their contractors," said Mark Serwotka, PCS general secretary.

A spokesperson for Fujitsu said: "Fujitsu is disappointed PCS has decided not to ask its members to vote on our pay offer, which we believe is a fair one, but has decided instead to ask them to vote on whether to take industrial action.

"Fujitsu is committed to working with PCS to resolve these issues and to implement a pay review for members and indeed we are meeting with them and ACAS for further talks next week."

Fujitsu has also recently , who were protesting against the sacking of union activist Alan Jenney. This was also intended to have an impact on a number of Fujitsu's government contracts, including with the Home Office and HMRC.