A no-deal Brexit departure from the EU could have a "serious effect" on the police's ability to fight crime, a watchdog has warned.
Paul Wiles, Biometrics commissioner, raised the concerns in his annual report.
In the document, submitted to Parliament on Thursday, he said: "The last year has been dominated by concern about the possible effects of Brexit on European exchanges and cooperation.
"If, in the event, the UK is excluded from the main exchange mechanisms, that would have a serious effect on the police ability to deal with inter-country and international criminality.
"The police have been working on mitigation planning but this will not remove the risks involved."
He said EU exchanges would be "continued as part of a Brexit deal or, if we leave without a deal, they will cease".
Mr Wiles also questioned if new rules for the use of fingerprints and DNA were stalling due to ministers having a focus on Brexit instead.
In the report, he said: "Home Office ministers currently show no sign of proposing a new legislative framework with specific rules to govern the police use of new biometrics in England and Wales.
"I do not know whether this is because they disagree with the need for such legislation or whether this is just another casualty of the need to focus on Brexit matters."
Additional reporting by the Press Association.
