The TUC has launched a report urging employers to give ex-offenders a fresh start in the New Year.
The report suggests getting ex-offenders into jobs is a good way to reduce the chances of them re-offending.
It also shows that many job applicants have committed crimes but do not have a criminal record, with only 3 to 4 per cent of crimes against individuals and their property resulting in a conviction or caution.
The study claims there are cases where a criminal record can be relevant to a job, suggesting it is in an employer's interest to encourage voluntary disclosure so they can judge whether or not this is the case.
It finds that blanket discrimination makes it less likely that job applicants will volunteer this information.
The report concludes that ex-offenders are more likely to disclose their records if they are sure they will have a fair chance of finding jobs they are qualified for, and where their offence is not relevant.
"All of us are less likely to be the victims of crime if we can help ex-offenders into work - it's the most effective way of preventing them from re-offending, said TUC General Secretary John Monks.
He stressed that there is a strong business case for fair treatment ñ with many workers with a criminal record contributing to the success of their company.
"Unions have always campaigned for full employment," he said. "This report presents evidence that a high proportion of unemployed people have a criminal record. If we want lower unemployment, then we must help ex-offenders into work. We know that many ex-offenders have low levels of skills and qualifications and the Government must tackle this as a priority."
The TUC guide employment and ex-offenders (ISBN 1 8500 6577 2) is available from TUC Publications 020-7467 1294 or at http://www.tuc.org.uk/exoffenders