Home Secretary John Reid has acknowledged there has been "fundamental flaws" in the system for processing details about people convicted of crimes abroad.

In a statement to MPs, he said police had identified the 540 "most serious" cases among a pool of more than 27,500 offenders. So far, details of 260 have been entered on the Police National Computer, he said.

However, 280 cannot be put into the system until more details are obtained from the countries where the crimes took place, he added.

The Home Secretary said the Criminal Records Bureau will check whether any vetting reports sent to employers about the most serious offenders need to be re-examined. He expected to be informed of the conclusions "in a matter of days".

Tom Hadley, the Recruitment and Employment Confederation’s director of external relations said: “It is of great concern that the Police National Computer is not fully up to date with information on foreign convictions. Recruiters rely on information from the Criminal Records Bureau to make the correct decision on who should work with children and vulnerable adults. This case highlights the importance of overall good recruitment practice.”