Workers at Fujitsu are beginning a six-day strike due to a dispute over redundancies and a pay freeze.
The strike starts today and will also take place on 7, 8, 11, 14 and 15 January 2010.
Workers who are members of the Unite union are unhappy with proposals for 1,000 redundancies in the UK, a pay freeze earlier this year, and plans to close the final salary pension scheme.
Unite says this is unreasonable when considered alongside Fujitsu's £200m profit last year and the £1.6m paid to two directors as "compensation for loss of office".
During the latest results announcement in October, the company announced that it beat its earnings target despite the challenging business environment.
Peter Skyte, Unite national officer for IT and communications, said, "Our members are angry with the way the company has treated them. Their pay has been frozen, compulsory redundancies are being pushed through and their pension scheme is under attack. All of this is happening at a time when the company is making substantial profits."
He said the company is using the recession as an excuse to reduce pay. "Members would prefer not to strike, but feel strongly that Fujitsu is not listening to their genuine concerns. We want the company to return to the negotiating table with a sensible offer acceptable to our membership."