More than half of call centres employ counsellors to help staff cope with abusive customers.

Having to talk to angry or aggressive callers on a regular basis has left many operators suffering from anxiety, a survey by Vocalis, which supplies speech recognition technology to the centres, found.

The 650,000 staff who work in calls centres in Britain typically get at least one abusive call a day.

Staff morale is increasingly a problem, according to the poll of 277 call centre managers.

Forty-two per cent of call agents suffered increased anxiety and worry. To deal with abusive callers, 93 per cent of centres trained staff to deal with phone rage.

Another report, by market analysts Mintel, found nine out of ten people who used call centres complained the experience left them feeling angry and frustrated.

Only five per cent of consumers said they had never had any problems with the centres, while others complained about long waiting times, bad music and seemingly endless option menus to work through.

Many people were left in a bad mood by the time they eventually got to speak to the operator and often took their anger out on him or her.