Thousands of people in Suffolk and Essex, including pre-school children and pet owners, have had their details stored on internal council databases due to their deemed potential threat to staff, an investigation has found.

Authorities across England identified more than 25,000 service users whose details are flagged on registers referred to as cautionary contacts lists (CCL), to warn staff of a potential risk to their safety.

The Press Association received the data through Freedom of Information responses from 76 authorities.

In some cases, authorities highlighted residents’ criminal records, history of violence against women, religious fundamentalism and aggressive behaviour towards employees as a reason for their inclusion.

Suffolk County Council said there were 2,377 people on its register, with 163 of the records for violence, although the vast majority were unspecified. Twelve referred to dangerous pets.

In Essex, a four-year-old deemed “physically or sexually threatening” and two three-year-olds for being violent to staff or other professionals were flagged on the county council’s own social services database.

Essex County Council said young children included on the list had been flagged “as a result of concerns about other people in their households/families”.

“It is important to emphasise that the list provided has been compiled specifically in response to the Freedom of Information Act request and we do not hold a cautionary contact list,” the council added.

“The records used to compile the list come from our social services database, where people can be flagged if concerns are raised.

“We have a duty of care to our employees and take their safety extremely seriously.

“It is very important that appropriate measures are in place to make them aware of risks and protect them from potential harm.”

At other councils CCLs included a man who keeps a “samurai sword over his front door and a mallet by his bed”, another armed with “a machete, catapult and axe” at their home, and one man who attempted to knock down two council workers with his van.

Others identified safety hazards within the client’s home, as well as examples of racist and homophobic behaviour - including a woman who expressed anti-Muslim views and wanted to choose the ethnicity of the staff member she dealt with.

Some councils identified a number of registered sex offenders on their list, while one council added a client to their database for accessing extremist websites.

Almost 1,500 service users were identified as not to be visited by a lone council worker, a woman, or at all.

A Local Government Association spokesman said: “Councils have a duty of care to their employees to ensure they are safe and aware of risks when carrying out their work.

“Local authorities keep cautionary contacts lists purely to protect staff who are in regular contact with local residents and businesses.

“Councils take their responsibilities under data protection law very seriously and, despite limited resources, are investing in robust systems to further safeguard confidential information prior to the implementation of the General Data Protection Regulation in May 2018.

“As far as we are aware, local authorities have complied with the law in the way they are recording data while maintaining these lists.”