The Police Service of Northern Ireland (PSNI) has since confirmed the poster was a fake, containing incorrect details.

It follows a major data breach last month - when the details of about 10,000 officers and staff were mistakenly published online.

The poster was found on Thursday night on Chapel Road in Dungiven, County Derry.

PSNI Assistant Chief Constable Chris Todd said: "This was a clear attempt to intimidate police officers, staff and their families but police can confirm that the information contained on the poster is incorrect.

"We have commenced an investigation into this matter and I appeal to anyone with any information relating to this incident to contact police on 101.

"We are particularly keen to hear from anyone who was travelling through Dungiven last night and who has any dash cam footage."

He had previously said the force had "contacted those involved to make them aware and recognise the impact this may have on them and their families".

"The safety and welfare of all our officers and staff remains our priority, and additional security and reassurance patrols have already been implemented across Northern Ireland as part of our organisational response," he added.

The personal details of around 10,000 PSNI officers and staff - including their surnames and first initial, rank or grade, where they are based for work and the unit they are employed by - were mistakenly released online in August in response to a Freedom of Information request.

The PSNI confirmed dissident republicans have access to the list shortly after a redacted version was posted near a Sinn Fein office in west Belfast last month.

A man appeared in court in Co Antrim on 19 August charged with two terror offences relating to the data breach.

Officers and their representative organisations have spoken out in recent weeks over concerns for their safety.

An independent review of the circumstances of the data breach is to be carried out, led by City of London Police Assistant Commissioner Peter O'Doherty.

Read more:
Why the police data breach is so serious
Officer's wife says they are 'living in fear' after leak

Several other data breaches have since emerged, including the loss of a police officer's laptop and notebook which contained details of 42 officers and members of staff after the items fell from a moving vehicle.

In a separate incident, a document containing the names of officers and staff was stolen, along with a police-issue laptop, from an officer's car on 6 July.