Police cannot trace more than 20 of the 80 most dangerous foreign prisoners freed in the UK without facing deportation because their details are not on the Police National Computer
As a result, the Association of Chief Police Officers has asked regional police forces to search their own databases for the missing 22 foreign nationals.
But as the Home Office has only supplied limited information, in some cases only a surname, local forces are struggling to find them.
Those being sought include at least one murderer and one rapist.
Earlier this week, it was revealed that 1,023 foreign prisoners had been released without being considered for deportation between 1999 and last month, because of poor communication between government departments.
The courts often make a recommendation for deportation once a convicted foreign national has served their sentence.