Fingerprints and DNA profiles were lost from the Counter Terrorism Command database in 2018, it has been revealed.
Bungling officials have lost the fingerprint records or DNA profiles of 144 potential terror suspects.
Nineteen were from people who 'may have posed a threat to national security', a report by Biometrics Commissioner Prof Paul Wiles said.
They were lost from the database of Counter Terrorism Command database in 2018, a year after 36 people died in attacks in London and Manchester.
MI5 rates the current threat level as severe.
But according to the latest annual report, scores of profiles of potential suspects were lost.
A table in his report outlines 'losses of biometric material of potential CT (counter-terrorism) interest for the year ending 31 December 2018'.
The 141-page study says: 'Previous annual reports have recorded that a number of IT issues, procedural and handling errors have led to the loss of a significant number of new biometric records that could and should have been retained on the grounds of national security.'
'During 2017 most of these issues appeared to have been resolved, with the new biometrics of 13 additional individuals lost; a substantial improvement on previous years.'
'It is therefore disappointing to report that during 2018 the new biometrics of 144 additional individuals have been lost.'
A breakdown shows 73% of the losses were blamed on 'an administrative error made during a manual data transfer to the software application used to manage NSDs (national security determinations)'.
Of the other losses, it says: 'Eight cases were not reviewed by Chief Officers before the relevant biometrics reached their statutory deletion date, so the NSD could not be made.'
'Eight cases were not progressed on time by the Counter-Terrorism Command.'
'The remaining 24 losses were recorded as lost by MPS (Metropolitan Police Service) forensic services as the result of an oversight in notification after the Schedule 7 stop had taken place.'