Police are scrambling to recover more than 150,000 records wiped from a major database after a blunder during routine maintenance.
The Police National Computer (PNC) is accessed 600 million times a year by officers, for information to support local, regional and national investigations.
Earlier this week, a software error caused 150,000 arrest records and thousands of other pieces of information to be deleted, The Times reported.
“While the loss relates to individuals who were arrested and then released with no further action, I have asked officials and the police to confirm their initial assessment that there is no threat to public safety,” he said.
“A fast time review has identified the problem and corrected the process so it cannot happen again.”
Individuals who are released with no further action because of a lack of evidence may still be subject to investigation, and records are key to potential arrests at a later date.
Mr Malthouse said the deletion happened during a standard housekeeping process that runs on the PNC.
The minister later told ITN that because of human error, defective code was introduced as part of routine maintenance earlier this week.
He said he was unsure whether the deletions would have an operational impact, but contingency measures had been put in place to allow the police to continue with their investigations.
Asked whether future cases would be jeopardised and victims affected, Mr Malthouse said officials were working to recover the data.
“What we’ve said to those who are currently relying on PNC data for investigations is that once we’ve done that, they can re-run their searches and hopefully get the result that they need,” he said.
The blunder hit police officers using a range of new processes for the first time following the end of the Brexit transition period.
More than 40,000 alerts from EU countries had already been deleted from the PNC after the UK was cut out of a European crime database.
In another blunder in October, the PNC went down for several hours after reportedly being accidentally unplugged.
Nick Thomas-Symonds MP, Labour’s shadow home secretary, said: “This is an extraordinarily serious security breach that presents huge dangers for public safety.
“The incompetence of this shambolic government cannot be allowed to put people at risk, let criminals go free and deny victims justice.
“The home secretary must take responsibility for this serious problem. She must – urgently – make a statement about what has gone wrong, the extent of the issue, and what action is being taken to reassure the public. Answers must be given.”