Remploy stunned union officials when they announced that almost half its 83 sites are to close or be merged under moves to transfer resources from loss-making factories into placing disabled people into mainstream jobs.

The company pledged that no disabled person would be made compulsorily redundant and said anyone wishing to continue working would be able to do so. Chief executive Bob Warner said: "We have a great opportunity to help more disabled people find jobs."

Union officials and workers reacted with shock and anger to the announcement, which is expected to lead to a ballot for industrial action. Phil Davies, national officer of the GMB said: "This is an act of industrial sabotage which the Government and the Remploy board of directors are trying to impose on disabled people and their families.

"The 43 factory closures are in areas of high unemployment. We believe that the whole of the trade union movement will support our fight to secure these jobs and these factories. The trade unions will now seek authority for a national official strike ballot in all 83 Remploy sites."

Mr Davies also criticised six charities which have supported the closure plans, accusing them of acting in a "despicable manner".

Jennie Formby, national officer of Unite, said: "The sheer scale of the closures and its impact on disabled workers is both shocking and unprecedented."

Les Woodward, a disabled worker based in Swansea, South Wales, said: "We feel frustrated and totally betrayed by the company and the Government. This has come as a complete shock to us all - we did not expect such decimation. They have declared war on us."

Remploy said 2,270 disabled people and 280 non-disabled workers will be affected by the changes. Mr Warner said every job in a Remploy factory costs more than £20,000 to support and for the same money the company can place four people in jobs with mainstream employers.

Remploy said it had an "ambitious" programme to transfer resources from loss-making factories to support more than 20,000 disabled people into jobs in mainstream employment every year. As well as the factory closures and mergers, there will also be reductions in management and central overheads. Remploy said it will work with other local employers to find jobs in mainstream employment for people affected by Tuesday's announcement.