Employees who feel unappreciated or badly treated are keeping good ideas and skills to themselves to help them to win better jobs, according to researchers at Birkbeck College at the University of London.

They have discovered that up to one in five employees believe that it is not in their best interests to share their good ideas freely with colleagues or bosses, preferring to hoard their knowledge to try to win promotion or move to another employer.

Adrian Patch, a research psychologist who interviewed more than 900 people working in information technology, the media and healthcare, said that employers were suffering because of their own ruthlessness after decades of promoting the idea that there is no longer such a thing as a job for life. This had encouraged employees to look after themselves.

"Organisations have been out for their own ends and now it is rebounding on them," says Mr Patch. "Employees are adopting this parasitic approach, looking after their own interests. Although knowledge-hoarders are in the minority, it does not mean the issue is trivial. A single instance of knowledge hoarding could conceivably have far-reaching effects."

From the research, nearly 20 per cent of media workers, 7 per cent of IT workers and 13 per cent of healthcare workers said that they believed that it was not in their best interests to share their expertise freely with colleagues. Ambitious employees who felt undervalued, ill-treated or who had little trust in their employer keeping promises were the most likely to hoard knowledge.

Mr Patch cited the example of a information technology specialist who had developed a quick and efficient way of dealing with a frequently occurring computer fault, but who refused to tell colleagues.

The growth of the knowledge-based economy, in which company success depended more on ideas and services, had led to a growth in knowledge hoarding just as companies introduced flexible working, such as short-term contracts, to reduce overheads. Employers wanting to avoid knowledge hoarding were urged to try to make workers feel valued.