Vast troves of highly sensitive police data are lying on Microsoft cloud platforms which an official UK security assessment deemed to be vulnerable to “compromise” by foreign actors and the US government, a Guardian investigation can reveal.

The files include criminal records, victim statements, internal emails and sensitive information held by more than 40 police forces across the UK.

Some files exceed “official” classification, according to a police document seen by the Guardian, raising the possibility the information could be classed as “secret” or “top secret”.