More than 150,000 fingerprint, DNA and arrest history records were deleted from the UK police database.
The error, which happened during a standard housekeeping exercise, may result in offenders being released because biometric evidence will not show up on the police national computer.
Intelligence on suspects was also deleted in error. The deletions could impinge on police powers to reopen investigations should more evidence come to light in certain cases.
Britain’s visa system was also affected and the application process was suspended for two days, although this has since been reinstated.
Kit Malthouse, the policing minister, said officers are “working at pace” to recover the deleted information.
The MP also told Home Office officials and the police to confirm that “there is no threat to public safety”.
But a former police chief said the “very large” deletion risks officers failing to identify suspects who have been released but go on to offend.
Former Cumbria police chief Stuart Hyde said the loss represents a “very large proportion” of about 650,000 people arrested each year and is a “risk to public safety and a risk to the safeguarding of vulnerable people across the country”.
"In terms of the risk this creates, clearly some of those people may be involved in subsequent offending and could only be identified through either fingerprints and DNA when they were subsequently brought to light. That may be only a few people, a handful, but nonetheless, it still represents a risk," he told BBC Radio 4's Today programme.
The shadow home secretary Nick Thomas-Symonds said Home Secretary Priti Patel should take responsibility for the “extraordinarily serious security breach” that “presents huge dangers for public safety”.
Alistair Carmichael, Home Affairs spokesman for the Liberal Democrats said that Ms Patel “must take responsibility and come forward to explain exactly what went wrong and how, and what she is doing to make sure it never happens again”.
He said: “This fiasco risks making our communities less safe and the police’s job even harder, at a time when they are already under enormous pressure.”