Up to a million people in Britain are workaholics, averaging 60 hours a week, but this addiction to work often hits their productivity and personal lives, research showed yesterday.

Managers, craft and professional workers are most likely to put in extra hours, blaming heavy workloads or "sheer love of the job". But 75 per cent of people working more than 48 hours a week said they had made mistakes due to tiredness.

Only a few believed workaholics were more productive.

A third of people working long hours said relationships had been strained, while one in eight said they had broken up with their partner.

The UK Institute of Personnel and Development said its survey of 8,000 people showed one in three working more than 48 hours claimed to be addicted to their job. "While it is true that many people are straining under heavy workloads, the results suggest there is still scope for organisations and individuals to find ways of working smarter rather than harder," said the report's author, Ms Melissa Compton-Edwards.