The Arts Council of England has warned British museums of a “SEVERE AND IMMINENT” threat of “attack.”

The warnings originate with England’s National Crime Agency, which fights economic crime and cyber crime, and is involved with border policing.

According to a source in Scotland, the National Crime Agency “are aware of a group who have made reconnaissance visits to a number of museums and other venues across the UK.”

In a document obtained by artnet News from an agency that received the warning, William Brown, the Arts Council’s National Security Adviser, urges heightened vigilance, advising museums to use their “best available defence,” treating any alarms “with professionalism and suspicion.”

The threat comes when museums’ funding has been severely cut, with experts warning that staff will be decimated. Museums have even resorted to selling off works to raise funds, facing sanctions from oversight organizations.

A representative of the Arts Council specified that theft is the organization’s highest concern. Burglars hit the National Museum of Scotland in September, making off with rare medieval coins. That theft may have taken place during a strike.

Brown instructs museums to use extra vigilance toward any visitors “paying undue attention to collections” and to clean display cases so that forensic evidence such as fingerprints is obtainable in case of theft.

The Art Newspaper speculates that underworld sources may have warned officials of the possible attacks or theft.