Hector Mackenzie, general secretary of Cohse, the health service union, said sweeping confidentiality clauses were 'quite breathtaking' in their implications.
He quoted a clause from the contract for St Bartholomew's National Health Service Trust in central London as an example of what was being demanded.
That contract restricted employees, during and following employment, from revealing any details of the trust's business, under the threat of disciplinary action. Supporting calls for a positive framework of workers' rights, he said: 'This is not about the duty of health staff to maintain normal confidentialities, including information about patients and their diagnosis.
'This clause is designed to stop any information about developments in the trust, resourced out of public money being brought before the public.'
He challenged the Government, as the guardian of individual rights, to outlaw such gagging clausesas an infringement of civil liberties.