Nick Row, of the Independent Union of Halifax Staff, said call centres had removed any opportunity for meaningful interaction with customers or job satisfaction.

Regulation needed: Nick Row

"Being logged onto a computer for eight hours a day, having the duration of your calls monitored, having your every movement monitored by the technology, is not a way of working which any of you at congress would enjoy and which none of our members should be subjected to," he said.

New technology had altered the balance of mental and physical work, he said.

"Call centres operate in conditions mostly the same as traditional factories," he said.

The stress of technology

He blamed discretion being removed to software programmes, power dialling systems which left no gaps between calls, no control over the calls taken and exhausting shift patterns for "appallingly difficult and stressful" working environments.

"The practices which existed in factories in the past are now rearing their heads in financial services. We should not repeat the mistakes of the 19th century as we near the millennium."

Mr Row called for action to be taken now to provide job satisfaction for call centre staff.

He feared that regulations protecting consumers had failed to protect workers.

Tony Whitely, of the MSF union, backed Mr Row, warning: "Without proper regulation call centres may become the deliverers of a finance scandal far greater than the pensions mis-selling affair".

Thousands of sales professionals had to give "best advice", he said. But call centres did not offer advice, selling products on an execution-only basis, said Mr Whitely.