A third of British employers will not hire ex-offenders or those with a history of drug abuse or long-term sickness, new research has suggested.
It is illegal to discriminate against ex-offenders with 'spent' convictions
More than 60% deliberately exclude those termed "core jobless" from their recruitment process, said the Chartered Institute of Personnel and Development.
Of 750 employers surveyed, 36% thought such applicants would be unreliable.
A spokesman said: "More must be done by policy makers, working with employers, to address negative stereotypes."
EMPLOYERS WOULD EXCLUDE:
Those with a history of drug use: 36.1%
Those with a history of long-term illness: 33.1%
Homeless people: 24.1%
Those with a history of mental illness: 18%
Those with a history of long-term unemployment: 10.4%
New Deal participants: 3.3%
*Source CIPD survey of 750 employers
John Philpott, chief economist for the Chartered Institute of Personnel and Development (CIPD), said government initiatives such as Pathways to Work were to be welcomed.
The CIPD found that 55% of employers said nothing would persuade them to recruit the core jobless, but 10% thought appropriate public policy measures might help.
"But even a relatively slight cooling in the labour market, as now seems underway, is bad news for those at the back of the jobs queue and for ministers who may find it harder to meet their welfare reform objectives," Mr Philpott said.
He said that the government should make sure those regarded as unemployable would be helped and that employers were encouraged to take them on.
CIPD figures showed that of employers with experience of employing ex-offenders, for example, 87% considered them at least as productive as other workers and 75% at least as reliable.
The Confederation of British Industry (CBI) said, the tightness of the labour market meant it was becoming "an economic imperative" to consider all candidates with the skills for a job.
"But firms not only have reason to be cautious about taking on staff who pose a potential risk to other staff, customers or the assets of the business, they have a responsibility to do so," a spokesman said.
"Supervised schemes which create links between ex-offenders and employers may help overcome the real and perceived risks associated with employing offenders," he added.
The Rehabilitation of Offenders Act gives people the right not to be discriminated against if their conviction is "spent" - which effectively means some offences are wiped from the record after a certain amount of time.
Nacro, the crime reduction charity, said it had received calls from a number of ex-offenders who had been discriminated against.
Helpline manager Mervyn Barrett said: "Most ex-offenders are in the workplace and they are doing a job every bit as conscientiously as people with no criminal record.
"The overwhelming majority of people who call us with employment problems are those who have been affected by the new criminal record checks introduced in March 2002 when the Criminal Record Bureau was set up."
The checks give information held about people on the Police National Computer, and are designed to safeguard jobs that involve working with children or vulnerable adults.
But Mr Barrett claimed some employers were running checks for positions which fell outside these categories.
Mr Barrett said: "We are dealing with people who have been refused employment or suspended or dismissed on the basis of very old, minor or wholly irrelevant convictions or cautions.
The Home Office said the process by which employers became a registered body with the CRB established if they had a legal entitlement to see a job applicants' criminal record.
Registered bodies are provided with guidance on types of positions where a CRB check can be requested.
"The CRB has worked with the CIPD and Nacro to develop guidance to users of CRB checks on how to use CRB checks as part of a recruitment process," a spokeswoman said.
The CRB carries out assurance checks on registered bodies to ensure they comply with its guidance on their use.
The spokeswoman added: "Research carried out by the CRB shows that in nine out of 10 cases where a CRB check reveals conviction information, the applicant is still offered employment."