The personal details of thousands of people have been plastered over the internet by anti-badger cull protesters.

And activists have claimed some of the 7,000 people whose details were leaked are directly involved in the cull, naming a number of people from Dorset and the surrounding counties in a blog post.

South west firm Old Mill Accountancy, where the data originated from, has apologised for the leak, saying that a list of names and addresses was accidentally placed on a back-end page of its website earlier this year.

The data includes names and addresses – but no phone numbers, financial information or sensitive data – of 7,000 people, hundreds of whom live in Dorset.

Old Mill Accountancy removed the data as soon as it was made aware of the error, but the information has now been published on an anti-cull website.

As well as listing the full data of the 7,000 people whose details were leaked, the site has also identified people it claims are ‘badger cull company directors’.

A spokesman for the farmers union NFU said that it is ‘pure speculation’ on the part of the activists that these people have anything to do with the badger cull.

On Monday, the Dorset Echo revealed that policing the badger cull in 2017 cost Dorset Police more than £500,000. Almost 5,000 badgers were killed and the licence allowing the badger cull to go ahead this year in Dorset has been renewed.

In a statement, data protection officer for Old Mill Duncan Parkes said: “We can confirm that a contact list of names and addresses was accidentally placed on a back end-page of our website earlier this year. As soon as it was spotted, the list was removed.

“The list included names and addresses only. It did not include telephone numbers, email addresses or financial information. Every person on this list is being personally contacted by us with an apology for this error.

“We take our clients’ data protection very seriously and have strict policies, however on this occasion, we acknowledge we made an error and apologise for this. We have since updated all our processes and policies to ensure this human error does not occur again.”

He added: “The data list was spotted by an individual who contacted us on 8th July 2018. We immediately deleted the list. After specific requests from us, he confirmed in writing that he had also deleted the mailing list from his computer on 9th July 2018.

“We find it deeply frustrating and disappointing to hear that the data list has appeared on a separate website. We are now working with our solicitors, and the police, asking for it to be urgently removed. It goes without saying that we are doing all we can to resolve this issue as quickly as possible.”

The Information Commissioner’s Office, which deals with data privacy, said that Old Mill Accountancy has made it aware of the incident, and the information provided is being assessed.