Staff employed by businesses working on government contracts are to be covered by the same conditions as Whitehall employees, including the removal of any barriers to joining a union and the right to training.

A spokesman for Gordon Brown insisted the guidelines, which will cover the contractors that annually supply £150bn ($301bn) of goods and services to central government, would not change the law or introduce new rights for workers. He was responding to reports that contractors would be told they must promote trade union membership if they wanted to win government work.